Learning Objective

By the end of this lesson, the learner will be able to describe the epidemiology, risk factors, clinical features, major subtypes, prognostic indicators, and management of malignant melanoma.

Malignant Melanoma

Malignant melanoma is a malignant tumor of melanocytes with a rapidly rising incidence, most commonly affecting adults aged 40–70 years.
Major risk factors include chronic sun exposure, blistering sunburns, fair skin, and a family history of melanoma. Genetic alterations include loss-of-function mutations in CDKN2A (p16) and somatic mutations in NRAS and BRAF.

Clinically, melanoma presents as a pigmented lesion with a large diameter, asymmetry, irregular borders, and variegated color. Lesions may appear as macules, papules, or nodules.
Distribution patterns differ by sex:

• Males: upper back
• Females: back and legs

Subtypes of Melanoma

• Lentigo Maligna Melanoma
  Occurs on the face/neck of older adults; slow-growing with the best prognosis.
• Superficial Spreading Melanoma
  The most common subtype is characterized by a predominant radial (horizontal) growth phase.
• Acral Lentiginous Melanoma
  The most common melanoma in dark-skinned individuals affects palms, soles, and subungual areas.
• Nodular Melanoma
  A deeply invasive, vertically growing nodular tumor, associated with the worst prognosis.

Prognosis

Prognosis is determined primarily by Breslow thickness, a measurement of tumor depth of invasion.
TNM staging incorporates thickness, ulceration, and nodal/metastatic status.

Management

• Localized disease: wide surgical excision ± sentinel lymph node biopsy
• Advanced/metastatic disease: immunotherapy or chemotherapy
  Melanomas may metastasize after prolonged periods of dormancy.

Activity