Chapter 47. Diseases of the External Ear

Anatomy

Morphology

The pinnae of the external ear are cartilaginous frames that aid in focusing and localizing sound. Each pinna is anchored to the cranium by skin, cartilage, auricular muscles, and extrinsic ligaments. The anatomy of the pinna is illustrated in Figure 47–1.

The external auditory canal (EAC) is typically 24 mm in length with a volume of 1–2 mL. The lateral third of the canal is made of fibrocartilage, whereas the medial two thirds are osseous. During early childhood, the canal is straight, but takes on an “S” shape by the age of 9. The EAC has an important relationship with the mastoid segment of the facial nerve, which lies posterior to the EAC as it descends toward the stylomastoid foramen. The temporomandibular joint is anterior to the EAC, and disease processes affecting this joint may lead to otalgia.

Skin

The EAC is lined by stratified squamous epithelium that is continuous with the skin of the pinna and the epithelial covering of the tympanic membrane. The subcutaneous layer of the cartilaginous portion of the canal contains hair follicles, sebaceous glands, and ceruminous glands, and is up to 1 mm thick. The skin of the osseous canal does not have subcutaneous elements and is only 0.2 mm thick (Figure 47–2). The epithelium of the EAC migrates laterally, allowing the canal to remain unobstructed by debris. The rate of epithelial migration is 0.07 mm/d and is thought to occur at the basal cell layer.

The ceruminous glands are modified apocrine sweat glands surrounded by myoepithelial cells; they are organized into apopilosebaceous units (Figure 47–3). Cerumen prevents canal maceration, has antibacterial properties, and has a normally acidic pH, all of which contribute to an antibacterial effect of cerumen.

Innervation

The pinna is innervated laterally, inferiorly, and posteriorly by the great auricular nerve (cervical plexus). Arnold's nerve (a branch of the vagus nerve) innervates the inferior bony canal, the posterosuperior cartilaginous canal, and corresponding segments of the tympanic membrane and the cymba concha. The posterosuperior bony EAC is innervated by branches of the facial nerve. The auriculotemporal branch of V3 supplies the anterior portion of the pinna. The glossopharyngeal nerve contribution to the external ear is not well delineated.

Lymphatic Drainage

The anterior and superior wall of the EAC and tragus are drained by preauricular lymph nodes. The infraauricular lymph nodes drain the helix and the inferior wall of the EAC, whereas the concha and antihelix are drained by the mastoid nodes.

Vascular Supply

The posterior auricular artery and the superficial temporal artery arise from the external carotid artery and supply the auricle and lateral EAC. The deep auricular branch of the maxillary artery supplies more medial aspects of the canal and the external surface of the tympanic membrane. The posterior auricular and superficial temporal veins drain the external ear.

Physiology

The external ear aids in the efficient transmission of sound to the tympanic membrane by serving as a functional resonator and, in particular, boosts transmission in the speech frequencies.

The hairs in the lateral canal, as well as the depth and tortuosity of the EAC, protect the tympanic membrane and structures of the middle ear.

Embryology

The mammalian ear is divided into external, middle, and inner ear components, which differ in their embryologic origin (Figure 47–4). The external ear consists of the pinna, the EAC, and the tympanic membrane, and is embryologically derived from the first and second branchial arches, and includes both ectodermal and mesodermal components. The mesenchymal tissue of the arches is composed of paraxial mesoderm and neural crest cells. The pinna is formed by gradual change in shape and fusion of components of the six auricular hillocks, which are derived from the first and second branchial arches (Figure 47–5). The formation of the external auditory meatus results from an ingrowth of a solid epithelial plate of ectodermal cells, the meatal plug, which eventually resorbs with only the lining of the canal remaining. The canal is lined by epithelial cells of ectodermal origin. The tympanic membrane begins to develop during the 28th week of gestation and arises from the most medial aspect of the meatal plug, which eventually becomes the external layer of the tympanic membrane.

General Considerations

Congenital anomalies of the external ear include a spectrum of malformations of the pinna as well as varying degrees of atresia and stenosis of the EAC. The causes of these disorders may be genetic or secondary to environmental exposures. These disorders include variants of microtia, lop ear, cup ear, Stahl's ear, cryptotia, and prominent ear. Patient evaluation requires a thorough head and neck examination to exclude additional congenital anomalies. The list of associated syndromes is extensive and includes Goldenhar (hemifacial microsomia), branchio-oto-renal, Treacher Collins, and Robinow syndromes.

Pathogenesis

Multiple genes may have redundant roles in outer ear formation, which can account for phenotypically similar malformations. The sequence of such dysregulation is only beginning to be understood with the help of murine knock-out and knock-in models. The auricular hillocks that give rise to the pinna arise during the sixth week of embryogenesis, whereas the inner two thirds of the EAC are not formed until the 26th week. Untoward events throughout this period could give rise to structural anomalies of the external ear.

Microtia

Clinical Findings

Patients typically present at birth with obvious auricular malformations. Several classification systems are used to further subcategorize this entity, one of which is detailed below.

Grade I

The ear exhibits mild deformity, typically with a slightly dysmorphic helix and antihelix. This group includes low-set ears, lop ears, cupped ears, and mildly constricted ears. All major structures of the external ear are present to some degree. The lop ear is characterized by inferiorly angled positioning of the auricular cartilage and poor development of the antihelical fold, whereas the cup ear protrudes with a deep conchal bowl.

Grade II

All pinna structures are present, but tissue deficiency and significant deformity exist.

Grade III

Also known as, classic microtia or peanut ear, type III microtia has few or no recognizable landmarks of the auricle. The ear lobule is usually present and anteriorly positioned. This subgroup includes anotia, which is complete absence of the external ear.

Treatment

Classically, microtia has been treated by a multistage auricular reconstruction. Patients undergo observation until the age of five to allow for growth of rib cartilage, which is harvested for reconstruction, and the development of the contralateral ear. This approach offers the benefit of reconstruction with autogenous material, which ultimately requires little or no maintenance. However, it is difficult to achieve a perfect cosmetic result. Typically, reconstruction occurs in four stages.

Stage I: Cartilage Implantation

Rib graft is typically harvested from the chondrosis of ribs 6, 7, and 8. The goals of this stage include symmetry in the position of the reconstructed cartilaginous ear framework with the normal ear. Postoperatively, the patient must be assessed for pneumothorax, which may arise with rib harvest.

Stage II: Lobule Transfer

This procedure should be performed 2–3 months after Stage-I reconstruction and aligns the lobule with the reconstructed cartilage framework.

Stage III: Postauricular Skin Grafting

A postauricular sulcus is created to allow the ear to project away from the mastoid. This step should be performed 3 months after Stage-II reconstruction. Skin for the creation of the sulcus may be harvested from the groin, lower abdomen, buttocks, contralateral postauricular sulcus, or back.

Stage IV: Tragal Reconstructtion and Soft Tissue Debulking

This should be performed several months after Stage-III reconstruction.

Other Treatment Options

Another option for reconstruction includes the placement of a prosthesis. This can be either glued on or anchored to bone. If the patient selects a bone-anchored prosthesis rather than auricular reconstruction, he/she must be aware that daily maintenance is required and that the anchor may compromise the vascularity of the surgical site, complicating future reconstructive surgery if the patient becomes dissatisfied with the prosthesis. A prosthesis does offer the advantage of a minor surgical procedure and allows for auricular replacement at an earlier age than surgical reconstruction. Complications of all types of auricular reconstructions include infection, hematoma formation, skin-flap necrosis, scar contracture, and poor contouring.

Protruding Ears

Clinical Findings

An increase in the distance from the helical rim to the mastoid is thought to be due to a lack of the antihelical fold and prominence of the conchal bowl. Ideal distance has been described as 15–20 mm with an ideal angle of 30°. Greater than 45° angulation is considered abnormal. This entity is most frequently bilateral.

Treatment

Otoplasty is the mainstay of treatment for protruding ears. Often used techniques include recreating the antihelical fold utilizing 2–4 horizontal mattress sutures through the cartilage and anterior perichondrium (Mustarde technique). Stiff cartilage may require additional contouring. Conchal excess may be treated by removal of soft tissue and skin from the postauricular sulcus followed by concha-to-mastoid sutures at the fossa triangularis, cavum concha, and cymba concha.

Complications

Excessive overcorrection of the middle third of the ear should be avoided to prevent development of the “telephone ear” deformity. Hematoma is the most common complication following otoplasty occurring in approximately 3% of cases. Lack of patient satisfaction, although not a true complication, is not an uncommon occurrence as loss of up to 40% of correction has been reported.

Atresia & Stenosis of the External Auditory Canal

Clinical Findings

Congenital anomalies of the EAC range from mild stenosis to complete atresia. These are often seen in association with malformations of the pinna and the structures of the middle ear. A canal cholesteatoma can develop in the face of severe EAC stenosis, and may also occur with epithelial rests left behind the atresia plate.

Audiologic evaluation via behavioral or electrophysiologic measures should be performed to confirm normal hearing in the contralateral ear in unilateral disease, and to assess for ipsilateral sensorineural hearing loss. The typical pattern of hearing loss in affected ears is a conductive hearing loss of 50–70 dB. Axial and coronal computed tomography (CT) scans are essential in the evaluation of patients with canal atresia or stenosis. CT scanning assesses for ossicular, facial nerve, and otic capsule abnormalities as well as for the degree of temporal bone pneumatization. In addition, CT scanning can be used to identify a cholesteatoma that would necessitate earlier surgical intervention.

Treatment

A discussion on reconstruction for aural atresia can be found in Chapter 48, Congenital Disorders of the Middle Ear.

The external ear is subject to a wide variety of injuries. All trauma patients require appropriate stabilization and triage of associated injuries based on their severity. Adherence to basic surgical principles and wound care prevents complications and improves the likelihood of a successful outcome.

Auricular Hematoma

Essentials of Diagnosis

• History of auricular trauma
• Edematous, fluctuant, and ecchymotic pinna with loss of normal cartilaginous landmarks
• Early diagnosis and treatment necessary to minimize cosmetic deformity.

General Considerations

Auricular hematoma refers to the accumulation of blood in the subperichondrial space, usually secondary to blunt trauma.

Pathogenesis

Cartilage lacks its own blood supply and instead relies on the vascularity of the perichondrium via diffusion. Shearing forces secondary to blunt trauma to the pinna lead to an accumulation of blood in the subperichondrial space. This creates a barrier for diffusion between the cartilage and the perichondrial vascularity, leading to necrosis of the cartilage and predisposing it to infection and further injury.

Clinical Findings

A patient with an auricular hematoma usually presents with an edematous, fluctuant, and ecchymotic pinna, with loss of the normal cartilaginous landmarks. Failure to evacuate the hematoma may lead to infection and/or cartilage necrosis and permanent disfigurement known as “cauliflower ear.”

Treatment

The evacuation of hematomas can be performed using a skin incision parallel with the natural auricular skin folds. The irrigation of evacuated hematomas with topical antibiotics reduces the likelihood of infection. Splinting after drainage prevents the reaccumulation of hematomas, and options include cotton bolsters, plaster molds, silicon putty, and water-resistant thermoplastic splints. Through-and-through whip-type absorbable mattress sutures without a bolster have also been described.

Auricular Lacerations

Sharp or severe blunt trauma may lead to laceration or avulsion of the auricle. The expeditious repair and prevention of infection are essential. Auricular lacerations should be cleansed and débrided prior to repair. Simple lacerations can be closed primarily, whereas extensive injuries with tissue loss may require undermining, flap reconstruction, or tissue grafts. In the case of a near-total ear avulsion still attached to the helical root, the ear can be successfully reattached as the supply of the upper auricular-helical artery seems to be sufficient for the entire ear. Leech therapy may be required to support venous outflow until neovascularization occurs. Repairs should be covered with pressure dressings to prevent edema and hematoma formation, and cartilage-penetrating antibiotics such as quinolones should be prescribed. Excellent cosmetic results can be achieved, even with extensive lacerations.

Otitis Externa

Essentials of Diagnosis

• Otalgia, otorrhea, pruritus, hearing loss, history of water exposure
• In severe cases in which edema occludes ear canal, wick is critical to maintain EAC and permit antibiotic drops to reach infected tissues
• Cases in which erythema and tenderness extend outside of EAC require oral antibiotics with antipseudomonal activity.

General Considerations

Otitis externa is an inflammatory and infectious process of the EAC. Pseudomonas aeruginosa and Staphylococcus aureus are the most commonly isolated organisms. Less commonly isolated organisms include Proteus species, Staphylococcus epidermidis, diphtheroids, and Escherichiacoli. Fungal otitis externa is discussed in the next section.

Pathogenesis

In the preinflammatory stage, the ear is exposed to predisposing factors, including heat, humidity, maceration, the absence of cerumen, and an alkaline pH. Loss of acidity has been shown to be proportionate to the degree of infection. This can cause edema of the stratum corneum and occlusion of the apopilosebaceous units. In the inflammatory stage, bacterial overgrowth ensues, with progressive edema and intensified pain. Incomplete resolution or persistent inflammation for more than 3 months refers to the chronic inflammatory stage.

Clinical Findings

Symptoms of otitis externa may vary, depending on the stage and extent of disease. The clinical diagnosis is suggested by the presence of otalgia, otorrhea, aural fullness, pruritus, tenderness to palpation, and varying degrees of occlusion of the EAC. The patient may also present with hearing loss, which results from occlusion of the EAC by edema and debris. Signs of otitis externa include pain on distraction of the pinna, EAC erythema, edema, otorrhea, crusting, and, in more advanced disease, lymphadenopathy of the periauricular and anterior cervical lymph nodes. Skin changes of cellulitis may be present as well. In the chronic stage, the skin of the EAC may be thickened. A culture may be helpful for infections that are refractory to treatment.

Treatment

Treatment for otitis externa involves meticulous atraumatic debridement of the EAC with the help of a microscope. Analgesia can be achieved with nonsteroidal antiinflammatory drugs (NSAIDs), opioids, or topical steroid preparations. After cleansing is complete, otic drop preparations that are antiseptic, acidifying, or antibiotic (or any combination of these) should be used. These have been shown to be equally effective in the management of uncomplicated otitis externa in a recent Cochrane review. If the degree of stenosis of the canal is severe, a wick must be placed in an effort to stent open the EAC and permit delivery of drops to the medial portion of the canal.

Available antiseptic preparations include acetic and boric acids, ichthammol, phenol, aluminum acetate, gentian violet, thymol, thimerosal (eg, Merthiolate), cresylate, and alcohol. Available antibiotic preparations include ofloxacin, ciprofloxacin, colistin, polymyxin B, neomycin, chloramphenicol, gentamicin, and tobramycin. Polymyxin B and neomycin preparations are often used in combination for the treatment of Saureus and P aeruginosa infections. Ofloxacin and ciprofloxacin are single-agent antibiotics with an excellent spectrum of coverage for pathogens encountered in otitis externa. Preparations with steroids help to reduce edema and otalgia. Systemic antibiotics are indicated for infections that spread beyond the EAC. For chronic otitis externa, a canalplasty may be indicated for thickened skin that has caused canal obstruction. Patients must be instructed to avoid EAC manipulation and water exposure if they have a history of recurrent otitis externa (Figure 47–6).

Otomycosis

Essentials of Diagnosis

• Pruritus, otalgia, otorrhea, fullness, hearing loss, no response to topical antibiotics
• Fungal elements on physical examination
• Positive KOH preparation or fungal culture.

General Considerations

Otomycosis is an inflammatory process of the external ear canal due to infection with fungi and is responsible for more than 9% of the diagnoses of otitis externa. In 80% of cases, the etiologic agent is Aspergillus, whereas Candida is the next most frequently isolated fungus. Other more rare fungal pathogens include Phycomycetes, Rhizopus, Actinomyces, and Penicillium.

Pathogenesis

Otomycosis has similar predisposing factors to bacterial otitis externa. Patients with diabetes mellitus or an immunocompromised state are particularly susceptible to otomycosis. Patients with a mastoid bowl after a canal wall down procedure are predisposed to development of otomycosis as well.

Clinical Findings

Patients with otomycosis most frequently present with pruritus, aural fullness, and otorrhea, and may also complain of otalgia and hearing loss. The hearing loss associated with otomycosis usually results from the accumulation of mycotic debris.

Otoscopy often reveals mycelia, establishing the diagnosis. The EAC may be erythematous and fungal debris may appear white, gray, or black. Patients have typically been tried on topical antibacterial agents with no significant response. The diagnosis can be confirmed by identifying fungal elements on a KOH preparation or by a positive fungal culture.

Treatment

The treatment of otomycosis includes cleansing and debriding the EAC, acidifying the canal, and administering antifungal agents. Nonspecific antifungal agents include thimerosal (eg, Merthiolate) and gentian violet. Commonly used specific antifungals include clotrimazole, Nystatin (otic drops or powder), and ketoconazole. Topical ketoconazole, cresylate otic drops, and aluminum acetate otic drops were all relatively effective with >80% resolution rate on initial application. CSF powder (chloramphenicol, sulfamethoximazole, and fungizone) is also an excellent option.

Skull Base Osteomyelitis

Essentials of Diagnosis

• Immunosuppressed patients with intense otalgia, otorrhea, hearing loss, fullness, and pruritus
• Edema and erythema of the EAC, granulation tissue at the bony–cartilaginous junction, cranial neuropathies in advanced stages
• Elevated erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP). Culture of EAC. CT and/or technetium scan diagnostic; gallium scan to follow resolution of disease
• Biopsy is necessary to rule out carcinoma.

General Considerations

Skull base osteomyelitis, also known as malignant otitis externa or necrotizing otitis externa (NOE), is a bacterial infection of the EAC and skull base. This disease process is most frequently seen in elderly diabetics and immunocompromised patients. It most commonly begins as an external otitis that progresses to involve the temporal bone, and may progress to fatal meningitis, sepsis, and death if unrecognized or untreated.

Pathogenesis

Skull base osteomyelitis commonly begins as an external otitis that progresses to cellulitis, chondritis, osteitis, and, ultimately, osteomyelitis. Unlike otitis media, which spreads through the pneumatized portion of the temporal bone, NOE disseminates through the haversian canals and vascularized spaces of the skull base. As this progresses along the base of the skull, the facial nerve (stylomastoid foramen), hypoglossal nerve (hypoglossal canal), the abducens and trigeminal nerves (petrous apex), the glossopharyngeal, vagus, and spinal accessory nerves (jugular foramen) may be involved. Cranial neuropathy has classically been considered to portend a poor prognosis, although recent data has not supported a difference in mortality.

The most frequently isolated causative organism is P aeruginosa, which may exhibit high levels of antibiotic resistance. Aspergillus may also be an etiologic organism and is thought to originate from the middle ear or mastoid. Elderly diabetics are thought to be particularly susceptible because of the microangiopathic changes that blunt an already attenuated immune response. The cerumen of diabetic patients has also been described to be more acidic in nature, further contributing to their susceptibility.

Clinical Findings

Symptoms and Signs

Patients may present with intense otalgia, otorrhea, aural fullness, pruritus, and hearing loss. As the disease advances to involve the temporal bone, granulation tissue is seen on the floor of the EAC at the osteocartilaginous junction. Bony sequestra can also be found in the EAC. Edema, periaural lymphadenopathy, and trismus may be present. Cranial neuropathies occur in more advanced presentations of disease, and the facial nerve is the most frequently affected cranial nerve. Further progression may lead to sigmoid sinus thrombosis, meningitis, sepsis, and death.

Diagnostic Tests

Inflammatory markers such as ESR and CRP may be elevated. Cultures and sensitivity should be obtained to help in selecting appropriate antibiotics.

CT and MRI are useful in the initial evaluation to determine the extent of disease. Bone scans are sensitive for assessing bony involvement but are not specific (Figures 47–7, 47–8, and 47–9). Gallium scans are used to track the resolution of the infection, since bone scans often remain positive long after the infection has resolved (Figure 47–10).

Differential Diagnosis

Carcinomas of the EAC, chronic granulomatous disease, Paget disease, fibrous dysplasia, and nasopharyngeal carcinomas must be considered in the differential diagnosis. As carinoma of the EAC mimics many features of NOE, a biopsy is requisite to rule out carcinoma.

Treatment

Long-term parenteral antibiotics are the treatment of choice. Aminoglycosides (eg, tobramycin) and antipseudomonal β-lactam antibiotics, including piperacillin, ticarcillin, or ceftazidime, may be used. Some physicians recommend the use of outpatient fluoroquinolones such as ciprofloxacin or ofloxacin; however, this is appropriate only for patients with early presentations who can be followed up closely. Control of hyperglycemia and immunosuppression is necessary to maximize treatment. Surgical debridement may be necessary to remove necrotic tissue. Circumferential petrosectomy has been described as a method for surgical debridement with hearing and facial nerve function preservation. The use of hyperbaric oxygen has been described in cases refractory to antibiotics, with variable results. In an effort to prevent skull base osteomyelitis, all diabetic and immunocompromised patients must be followed up closely and treated aggressively if they present with symptoms suggestive of external otitis.

Essentials of Diagnosis

• Atopic dermatitis—pruritic erythematous patches or weeping plaques
• Psoriasis—oval salmon-pink plaques with silvery scales on elbows, knees, scalp, and buttocks
• Contact dermatitis—pruritic, indurated, and erythematous lesions after exposure to allergen or irritant.

Atopic Dermatitis

General Considerations

Atopic dermatitis is a chronic skin disease of immune-mediated origin. It may remit spontaneously or endure as a chronic condition. Lesions presenting on the ear may be pruritic and erythematous. Patients often have a personal or family history of atopy and allergy.

Atopic dermatitis often manifests in infancy on extensor surfaces and the face. Children may present with skin lesions on flexural areas and on the hands.

Pathogenesis

Though not completely understood, the clinical presentation of atopic dermatitis is thought to be secondary to immune dysfunction. Atopic skin lesions have been shown to have higher levels of Th2 T-lymphocytes, which produce inflammatory mediators such as interleukin 4, 5, and 10.

Clinical Findings

The diagnosis of atopic dermatitis is a clinical one. There is variability in skin lesions ranging from erythematous patches to weeping plaques. Lesions presenting on the ear are often pruritic and erythematous. Lesions typically persist for more than 1 month. Secondary infections with S aureus, herpes simplex virus, vaccinia, and molluscum contagiosum may occur.

Atopic dermatitis is characterized by the absence of specific laboratory and histologic markers. Elevated IgE and eosinophilia may be present yet are not specific for the diagnosis.

Differential Diagnosis

The differential diagnosis includes seborrheic dermatitis and psoriatic dermatitis.

Treatment

Topical corticosteroids are the mainstay of treatment. Antihistamines and lubricants may be used for the treatment of accompanying pruritus. Moisturizers and mild soaps are preferred to minimize exposure to potential allergens found in many cosmetic products. Food elimination and desensitization are not recommended. Though often self-limited, the disease may recur spontaneously and can become chronic. Bacterial superinfection may require topical and systemic antibiotics.

Psoriasis

General Considerations

Psoriasis is a chronic inflammatory disorder of the skin. Eighteen percent of patients with psoriasis have some involvement of the external ear, which may be secondary to extension from the scalp. Plaques may present on the concha and meatus of the EAC and are variably pruritic.

The incidence of psoriasis in the United States ranges from 2% to 5%. Males and females are equally affected, with the onset of disease typically occurring in adolescence.

Pathogenesis

The cause of psoriasis is unknown, yet there is a strong genetic component. Attacks of psoriasis may be triggered by certain drugs such as NSAIDs, beta-blockers, lithium carbonate, and antimalarial agents, as well as by infection, trauma, and stress.

Clinical Findings

Psoriasis is characterized by erythematous papules that coalesce to form round or oval salmon-pink plaques with silvery white scales found on the elbows, knees, scalp, and buttocks. These lesions bleed in pinpoint areas when scratched (Auspitz sign). Opacification or “oil spots” of the nails, as well as pitting and subungual hyperkeratosis, are also suggestive of this disease. Psoriatic lesions may present over areas of trauma, an entity known as Koebner phenomenon. Psoriatic arthritis occurs in 5–10% of all psoriatic patients.

Treatment

Patients should avoid excessive drying of the skin. For ears and face, treatment includes low-dose topical nonfluorinated corticosteroids such as alclometasone, mometasone, desonide, clocortolone, hydrocortisone valerate, and butyrate creams and topical calcipotriene. Warm-water soaks, 1–5% coal tar treatment, and topical anthralin C may also be helpful. Oral psoralens and UVA phototherapy for patients with widespread disease may be necessary. Antihistamines are used to treat the associated pruritus. Methotrexate may be required for severe cases and for psoriatic arthritis. The response to treatment is variable, and the condition may become chronic.

Contact Dermatitis

General Considerations

Contact dermatitis can be an acute or chronic inflammatory disorder of the skin caused by contact with an allergen or irritant. This process may occur anywhere along the pinna or the EAC. Eruption may occur secondary to instrumentation, foreign objects—including jewelry, earplugs, and hearing aids—and other objects used to scratch pruritic lesions. In addition, cosmetics and hair products are frequent culprits.

Pathogenesis

Allergic contact dermatitis is a Type IV hypersensitivity reaction, and cutaneous manifestations are often delayed by 1–3 days. This is in contrast to irritant-mediated contact dermatitis, which usually manifests earlier.

Clinical Findings

Allergic contact dermatitis is characterized by an indurated, erythematous, pruritic, and poorly demarcated process. This is in contrast to irritant dermatitis, which often presents with well-defined areas of exposure.

Skin testing to identify contact allergens may be of use.

Treatment

The avoidance of exposure to irritants and allergens and high-dose topical glucocorticoids are the mainstays of therapy.

First Branchial Cleft Anomalies

Essentials of Diagnosis

• Cyst or tract along anterior border of sternocleidomastoid muscle usually near angle of mandible
• Recurrent neck or ear drainage and infection
• CT scan may be helpful to identify tract
• Work classification system describes anomaly and relationship to facial nerve.

Pathogenesis

First branchial cleft anomalies occur as a result of anomalous fusion of the first and second branchial arches, with incomplete obliteration of the first branchial cleft.

Clinical Findings

Patients may present with a cyst or tract along the anterior border of the sternocleidomastoid muscle near the angle of the mandible. A membranous band between the medial aspect of the floor of the ear canal and the tympanic membrane at the manubrium of the malleus is also highly associated with first branchial cleft anomalies. The patient may have a history of recurrent infection and drainage from the ear or neck.

The Work classification system has been used to describe first branchial cleft cysts. A Work type 1 anomaly duplicates the membranous EAC only. It is lined with squamous epithelium and opens to the external skin. It is located superficial to the facial nerve. A Work type 2 anomaly duplicates both the membranous and cartilaginous EAC. It has a variable relationship with the facial nerve.

Treatment

The treatment for first branchial cleft anomalies is complete excision. Incomplete excision predisposes the patient to recurrence and reinfection. The tract may be intimately involved with the facial nerve, which is at risk during excision. This necessitates early identification of the facial nerve as it exits the stylomastoid foramen and tracing distally through the lesion. A superficial parotidectomy type approach may be required for complete excision.

Auricular Frostbite

Essentials of Diagnosis

• Cold exposure
• Auricle initially numb, then subsequently painful
• Auricle initially pale, cyanotic, and hypesthetic, then subsequently erythematous with bullae.

Pathogenesis

Freezing temperatures lead to both direct cellular injury as well as vascular compromise. Prolonged exposure to cold temperatures can lead to vasoconstriction, cold-mediated dehydration, endothelial injury, thrombosis, and ischemia of auricular tissue. In the early stage, this process may be reversible, but over time, it leads to tissue necrosis.

Clinical Findings

Temperatures below 10°C may lead to hypesthesia, and the person is frequently unaware of impending frostbite. The ear is initially pale and then cyanotic. Ultimately, as the ear thaws, pain, erythema, and subcutaneous bullae secondary to extravasated extracellular fluid or blood may develop.

Treatment

The initial treatment for auricular frostbite consists of rapid rewarming of the ear to 40–42°C. Nonhemorrhagic blisters may be débrided, and patients should be given pain medicine and antibiotics. Aloe vera has antithromboxane properties and, together with ibuprofen, may help in re-establishing circulation. More aggressive débridement should be delayed for several weeks until demarcation is complete.

Auricular Burns

Essentials of Diagnosis

• Superficial burn—erythema and pain
• Partial-thickness burn—painful blisters
• Full-thickness and subdermal burns—painless, gray/black eschar.

General Considerations

Thermal injury can be classified by the degree of the burn. Superficial burns involve the superficial layer of the epidermis. Partial-thickness burns extend into, but not through, the dermis. Full-thickness burns extend through the full thickness of the dermis. Subdermal burns extend into the subcutaneous tissue, including fat, muscle, tendon, cartilage, and bone.

Clinical Findings

Superficial auricular burns present with erythema secondary to dermal capillary dilation and vessel congestion. These burns are red and moderately painful. Patients with partial-thickness burns usually present with blisters that blanch on direct pressure and are very painful. Deep partial-thickness burns are associated with less pain, and there may be an eschar. Full-thickness and subdermal burns are painless because dermal nerve endings have been destroyed. The wound surface is of varying color, but may be gray or black and charred.

Treatment

Superficial burns do not scar and may be treated with moisturizing creams. The blisters of partial-thickness burns should be débrided, and antibiotic ointment applied. When not deep, these burns heal without scarring as well. Full-thickness, subdermal, and deep partial-thickness burns of the auricle heal with scarring and contracture and may be complicated by suppurative chondritis. These burns should be treated with both topical (usually silver based) and systemic cartilage penetrating antibiotics. Early débridement and closure with skin grafts should be considered. Secondary reconstruction is usually performed at approximately 1 year after injury.

Foreign Bodies of the External Ear

General Considerations

Foreign bodies within the external ear may present in both children and adults. Common objects include erasers, pills, batteries, and insects.

Clinical Findings

Patients may present with pain, pruritus, conductive hearing loss, and bleeding. A persistent foreign body may lead to infection and the formation of granulation tissue. Batteries lodged within the EAC, when in contact with moisture, may cause liquefaction necrosis, low-voltage injury, or pressure necrosis of the EAC skin or tympanic membrane.

Treatment

The removal of foreign objects should be done in an atraumatic manner. Injury to the EAC is minimized with direct visualization using the operating microscope and proper instrumentation (eg, right angle pick, curet, forceps, and suction) as well as minimizing patient movement. In children, general anesthesia is often required. Irrigation may help dislodge cerumen or smaller objects. Cerumen impaction may require prior softening with an otic preparation. Two percent lidocaine may be used for the removal of insects both to achieve topical anesthesia and also to kill the insect. Complete occlusion of the EAC with cyanoacrylate adhesives (ie, “superglue”) may require surgical removal with a postauricular approach

Essentials of Diagnosis

• The majority of external ear carcinomas can be reconstructed primarily
• The AJCC system may be used to classify external ear carcinoma, while the Pittsburgh staging system should be used for carcinoma of the ear canal
• Lateral temporal bone resection is indicated for T2 or greater ear canal carcinoma
• Parotidectomy and neck dissection should be reserved for advanced lesions and/or palpable disease
• Survival with ear canal carcinoma is highly correlated with T stage at presentation.

Basal Cell Carcinoma of the Auricle

General Considerations

Basal cell carcinomas are the most common malignant neoplasm of the auricle, representing 45% of auricular carcinomas.

Pathogenesis

Chronic long-term sun exposure is the predominant cause of basal cell carcinoma. Specifically, UVB radiation has been identified as a major carcinogen. The incidence of cancer increases with age. Other risk factors include fair skin, outdoor occupations, and a history of skin carcinoma.

Clinical Findings

Patients may initially present with a skin lesion that is nodular, ulcerated, and/or bleeding. Basal cell carcinomas of the auricle typically occur on the posterior surface of the pinna and in the preauricular area. The diagnosis of any suspicious lesion should be confirmed with biopsy. CT scans and MRI may be used to evaluate advanced disease with tumor extension to the adjacent temporal bone and soft tissue structures of the head and neck. The overall rate of metastasis is 0.003–0.1%.

Staging

Basal cell carcinomas of the EAC can be staged using the American Joint Committee on Cancer (AJCC) general staging system for nonmelanoma cancer of the skin. This staging system is limited by the fact that it does not account for histologic subtypes or the anatomic variability of the skin of the external ear compared with other skin sites.

Differential Diagnosis

Given the variability of subtypes, the differential diagnosis includes benign nevi, amelanotic melanomas, cutaneous squamous cell carcinomas, eczema, and scleroderma.

Treatment

Nonsurgical Measures

Topical 5-Fluorouracil.

Radiation Therapy

Indicated for poor surgical candidates or unresectable lesions.

Surgical Measures

Curettage with Electrodissection

Operator dependent and typically used to excise nodular lesions and desiccate the base.

Cryosurgery

Indicated for small basal cell carcinomas (<1 cm) with well-defined borders.

Local Excision

Ninety-five percent of basal cell carcinomas <2 cm in size can be successfully treated with local excision with a surgical margin of at least 4 mm. Auricular reconstruction may be required for large defects.

Mohs Surgical Technique

Refers to complete micrographic excision of the tumor using intraoperative histopathology to assess for positive margins. This technique is particularly useful for recurrent basal cell carcinomas, those larger than 2 cm, or those with an aggressive histology. Five-year cure rates using Mohs technique should approach 97.1%.

Cutaneous Squamous Cell Carcinoma

General Considerations

Squamous cell carcinomas account for 20% of all cutaneous malignant neoplasms and commonly occur in elderly males.

Pathogenesis

Risk factors for squamous cell carcinoma include immunosuppression, advanced age, a nonhealing ulcer, and exposure to chemicals such as arsenic, soot, coal, tar, paraffin, and petroleum oil. The most important risk factor is exposure to UV radiation.

Clinical Findings

The appearance of these tumors is variable and includes plaques, nodules, and ulcerations. They may be friable and prone to bleeding. Auricular lesions frequently occur on the helix or preauricular region, but may occur on any sun-exposed areas.

CT scanning and MRI may be used to evaluate advanced disease with tumor metastasis to the adjacent temporal bone and soft tissue structures of the head and neck. The proper diagnosis should be made with biopsy. The overall risk of metastasis for cutaneous squamous cell carcinoma of the external ear is approximately 6–18%.

Staging

The AJCC system may be utilized for carcinoma of the external ear. AJCC staging systems for nonmelanoma cancer of the ear canal may also be utilized, but the University of Pittsburgh system (Figure 47–11) is more frequently used for staging squamous cell carcinoma of the temporal bone, as the AJCC does not account for the unique nature of tumors arising in the ear canal.

Differential Diagnosis

The differential diagnosis includes basal cell carcinoma, actinic keratosis, seborrheic keratosis, keratoacanthomas, scars, psoriatic lesions, melanomas, and sarcomas.

Treatment

Nonsurgical Measures

Radiation therapy may be indicated for unresectable lesions or those that may lead to significant cosmetic disfigurement with surgery.

Surgical Measures

Local Excision

Ninety-five percent of squamous cell carcinomas <2 cm limited to external ear can be successfully treated with local excision with a surgical margin of at least 6 mm. Auricular reconstruction may be required for large defects. T1 lesions of the EAC may be treated with sleeve excision with careful attention to deep margins. T2 lesions or greater necessitate lateral temporal bone resection. Subtotal temporal bone resection involves the piecemeal removal of structures medial to the tympanic membrane and may be necessary for T3 and T4 lesions. Facial nerve involvement may necessitate its resection and grafting with a nerve graft remote to the site of the tumor (ie, sural nerve).

Mohs Surgical Technique

This technique is particularly useful for recurrent lesions, those >2 cm, or those with an aggressive histology.

Neck Dissection and Parotidectomy

In all cases of palpable disease in the parotid and neck, and in the case of T3 and T4 squamous cell carcinomas, parotidectomy, neck dissection, and adjuvant radiation should be strongly considered.

Prognosis

In addition to the patient's age and overall immune status, the prognosis for squamous cell carcinoma is dependent on the histologic subtype, size, and location of the tumor. A better prognosis is associated with a well-differentiated histology. The 5-year cure rate for squamous cell carcinomas of the external ear range from 75% to 92%.

Squamous cell carcinoma of the EAC carries a much more dire prognosis with recent studies suggesting a range of 5-year survival of T1 tumors of 83% and T4 tumors of 25%. Facial nerve involvement and nodal disease are poor prognostic findings.

Melanoma of the External Ear

General Considerations

The incidence of melanoma in the United States is 11.1 cases per 100,000 individuals. Auricular melanoma accounts for 1% of all melanomas. Melanomas of the ear have a 10-year survival rate of 70%.

Clinical Findings

Most melanomas involving the ear present on the helix. Though initially painless, these lesions may change in size, ulcerate, and bleed. A thorough head and neck examination requires attention to enlarged lymph nodes that may occur with regional spread of disease.

The diagnosis of melanoma is dependent on the histologic evaluation of a biopsy. At a minimum, metastatic evaluation should include a chest x-ray to rule out lung metastases and liver function tests to rule out liver metastases. CT scanning and MRI have added sensitivity in detecting metastatic disease. Radio-nuclide bone scans can be used to diagnose bony metastases.

Staging

Melanomas may be staged using the staging system of the AJCC. This system incorporates the depth of invasion, measured in millimeters. Deeper lesions and lesions with ulceration are associated with higher stages and higher mortality rates.

Differential Diagnosis

The differential diagnosis is diverse and includes benign lesions as well as basal cell and squamous cell carcinomas.

Treatment

Nonsurgical Measures

Adjunctive radiation therapy may have a role in palliation.

Surgical Measures

The extent of excision, including surgical margins, is dependent on the histologic type and stage of disease. Management of the regional lymphatics is controversial and may include elective regional lymph node dissection and parotidectomy. Recently, sentinel lymph node biopsy has become a well-accepted approach in the management of the N0 neck for lesions more than 1 mm deep.

Prevention

The avoidance of and protection from sun exposure are important in preventing disease, as is early detection. Early detection is also extremely important in improving prognosis.

Glandular Tumors of the External Auditory Canal

Essentials of Diagnosis

• Otorrhea, fullness, otalgia, and conductive hearing loss.
• Sensorineural hearing loss indicates inner ear extension.
• CT and MRI to define tumor and surrounding anatomy.
• Biopsy essential.

Classification

Glandular tumors of the EAC are rare and include four types: (1) adenoid cystic carcinomas, (2) ceruminous adenomas, (3) ceruminous adenocarcinomas, and (4) pleomorphic adenomas.

Adenoid Cystic Carcinoma

These are capsular tumors most often found in salivary gland tissue. They have a predilection for perineural, perivascular, and fatty infiltration. Patients with perineural invasion often present with otalgia. Histologically, these tumors may show cribriform, tubular, or solid patterns of cellular arrangement. Lymph node metastases are rare, but late distant metastasis in particular to the lung are not an uncommon feature of these tumors.

Ceruminous Adenoma

Ceruminous adenoma consists of benign painless masses that may grow undetected for prolonged periods of time. Patients may present with a conductive hearing loss or otitis externa. They are histologically characterized by double-layered cuboidal or columnar cells, and the epithelium may show apical “snouts” of apocrine secretion.

Ceruminous Adenocarcinoma

These tumors share histologic features with ceruminous adenomas, but they have higher rates of mitoses and cellular atypia. Invasion into adjacent structures may be present, and lymph node metastases are rare.

Pleomorphic Adenoma

These tumors vary histologically but are characterized by epithelial and mesenchymal elements. These benign tumors do not display features of invasion.

Clinical Findings

Patients with glandular tumors of the EAC may present with otorrhea, aural fullness, otalgia, and conductive hearing loss. Sensorineural hearing loss signifies tumor extension into the inner ear. CT imaging is helpful in determining the amount of bony erosion and the size of the tumor. Generous tissue samples are important for histologic diagnosis.

Treatment

Benign glandular tumors are treated with wide local excision. Malignant tumors are treated with a variant of temporal bone resection, and consideration should also be given to adjuvant radiation. In the case of adenoid cystic carcinoma, parotidectomy should be considered as it has been associated with increased survival.

Osteomas & Exostoses of the External Auditory Canal

Essentials of Diagnosis

• Usually asymptomatic; may present with cerumen impaction, otitis externa, or conductive hearing loss
• Osteoma—pedunculated bony EAC lesion
• Exostoses—multiple EAC lesions.

General Considerations

Osteomas are benign osseous neoplasms. Exostoses are firm, bony, broad-based lesions composed of a lamellar bone (Figure 47–12). Exostoses are formed by reactive bone formation and have been associated with cold-water exposure. Both osteomas and exostoses arise from the bony portion of the EAC (Figure 47–13).

Clinical Findings

Osteomas are usually pedunculated and often have a vascular core (Figure 47–14). Exostoses commonly present as multiple lesions. Although most osteomas and exostoses are asymptomatic, occlusion of the EAC with an enlarged lesion may lead to cerumen impaction, external otitis, and a conductive hearing loss on audiogram.

Treatment

Most exostoses and osteomas require no intervention. If surgery is necessary, a transcanal or postauricular approach can be used, depending on the size of the lesions. The preservation of skin flaps speeds healing.

When used for long, earplugs have been shown to be protective against exostoses in patients with frequent cold water exposure.

We would like to acknowledge Eli Grunstein, MD, and Felipe Santos, MD, for their contribution to this chapter in the previous editions of CDT.