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Paranasal and Anterior Skull Base Anatomy

  • The paranasal sinuses develop from mesenchymal and ectodermal tissue.

  • The sinuses define the spaces for tumor development and bony margins are barriers for spread to adjacent tissue.

  • The numerous foramina in the ventral skull base host critical neurovascular structures and allow direct tumor spread.

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Margins for Tumor Spread Anatomic Route
Anterior Frontal sinus and septum
Superior lateral Orbits and supraorbital dura
Inferior lateral Pterygopalatine fossa
Posterior lateral Fossa of Rosenmuller
Inferior posterior midline Clivus and arch of C1
Superior posterior midline Sella
Superior Cribriform plate

Paranasal Sinus Neoplasm Epidemiology

  • Paranasal neoplasms vary from benign congenital malformations to high-grade malignancies.

  • Squamous cell cancer (SCC) is the most common malignancy occurring with a frequency of 1:200,000 per year in the United States.

  • Paranasal malignancies comprise less than 1% of all cancers and 3% of cancers of the upper aerodigestive tract.

  • 55% of cancers in the paranasal sinuses originate in the maxillary sinus, 35% in the nasal passage, and 10% in the ethmoids.

  • Tumors of the frontal and sphenoid sinus account for less than 1% of paranasal malignancies.

History and Presentation

  • Paranasal tumors are a diagnostic and therapeutic challenge because they initially mimic common inflammatory sinonasal disease leading to delayed diagnosis and higher stages at diagnosis.

  • Most common symptom: nasal obstruction.

  • Second most common symptom: neck lymphadenopathy.

  • Nasal: discharge, congestion, epistaxis, disturbance of smell.

  • Facial: infraorbital nerve hypoesthesia, pain.

  • Ocular: unilateral epiphoria, diplopia, fullness of lids, pain, vision loss.

  • Auditory: aural fullness, otalgia, hearing loss.

  • Oral: pain involving the maxillary dentition.

  • Constitutional symptoms: fever, malaise/fatigue, weight loss.

Associated Causative Factors

  • Squamous cell carcinoma (SCC): nickel, aflatoxin, chromium, mustard gas, volatile hydrocarbons, and organic fibers that are found in the wood, shoe, and textile industries

  • Adenocarcinoma: wood dust, woodworking, furniture making, leather work

  • Human papilloma virus (HPV) may be a cofactor in some tumors; however, this finding may be an association and not a cause and effect situation.

    1. Tumor suppressor protein inhibition by viral E6 and E7 proteins has not been well studied in paranasal sinus tumors.

Physical Examination

  • Head/face: midface/periorbital edema

  • Eye: proptosis, visual field deficits, extraocular motion restriction, fullness of eyelids, chemosis, ptosis

  • Ear: middle ear effusion (often unilateral)

  • Nose: nasal cavity mass

  • Oral cavity: loose dentition, palatal sensory asymmetry, trismus, malocclusion, erosion of mass into the oral cavity

  • Neurologic: cranial nerve (CN) deficits, which commonly include CN I, II, III, IV, V1, V2, VI

Diagnostic Nasal Endoscopy

  • Evaluate extent of tumor and attempt to determine the origin or base.

  • Perform Valsalva maneuver under direct visualization—expansion implies intracranial or major venous extension.

  • Evaluate for ease and safety of biopsy.

Diagnostic Biopsy

  • Consider obtaining ...

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