Melanoma

• • Predominately a disease of fair-skinned people

  • Only 15% of melanomas develop in preexisting nevi, the remainder arise de novo

  • Most important prognostic factors include:

  • -Vertical height of melanoma

    -Sentinel lymph node status

    -Number of positive lymph nodes

    -Presence of metastatic disease

  • Melanoma typically metastasizes by the lymphatic route in a predictable and orderly fashion

  • 4 histologic categories of melanoma:

  • -Superficial spreading, 70% of cases

    -Nodular melanoma, 15% of cases

    -Lentigo maligna melanoma, 4-10% of cases

    -Acral lentiginous melanoma, 2-8% of cases

  • Melanoma most commonly metastasizes to the lungs, liver, and brain but can also involve the bone, adrenals, heart, and bowel

Epidemiology

• • 3-fold increase in the incidence of melanoma in the United States in the past decade

  • Risk factors include:

  • -UV exposure

    -Multiple or dysplastic nevi

    -First sunburn at an early age

    -Freckles

    -Fair complexion

    -Reddish or blond hair

    -Blue eyes

    -First-degree relative with melanoma

  • 90% of melanomas are cutaneous lesions, while the remainder occurs in the pigmented cells of the retina, or the mucous membranes of the nasopharynx, vulva, and anal canal

  • 2% of melanomas present as metastatic disease to regional lymph nodes or distant sites without a known primary

  • 10% of melanomas occur in patients with familial dysplastic nevi syndrome

Symptoms and Signs

• • Lesions that are suspicious for melanoma can be identified by their clinical characteristics:

  • -Asymmetry

    -Border irregularity

    -Color (variable or dark pigmentation)

    -Diameter (> 6 mm)

  • Other clinical signs of melanoma include:

  • -Itching

    -Bleeding

    -Ulceration

    -Changes in a preexisting benign mole

  • Lymphadenopathy may be present in regional lymph node basins

Imaging Findings

• • CT or MRI: Most useful to detect metastatic disease, or in the evaluation of noncutaneous melanomas

  • PET scan: May demonstrate areas of metastatic disease not detected with conventional CT or MRI

• • Melanoma

  • Dysplastic nevi

  • Benign mole

  • Nonmelanotic skin cancer:

  • -Basal cell carcinoma

    -Squamous cell carcinoma

    -Merkel cell carcinoma

    -Dermatofibrosarcoma protuberans

    -Sarcomas

Rule Out

• • Synchronous melanoma lesions

  • In-transit melanoma metastases

  • Evidence of regional lymphadenopathy

  • Nonmelanotic skin cancer

• • Complete history with emphasis on risk factors

  • Thorough physical exam including regional lymph node basin assessment

  • Excisional biopsy (1-2 mm margins) or punch biopsy of the suspicious lesion

  • Fine-needle aspiration of palpable lymph nodes suspected of representing melanoma metastases

  • Chest film to evaluate for evidence of pulmonary metastases

  • Obtain more thorough radiographic evaluation (head, chest and/or abdominal CT) in high-risk patients that present with bulky lymph node metastatic disease (clinical stage III)

When to Refer

• • All patients diagnosed with melanoma should be evaluated by a dermatologist to assess for synchronous melanomas or other atypical nevi

  • Patients with lymph node or regional metastases should be evaluated by ...