Malignant Melanoma: Clinical Aspects and Management

Malignant melanoma is a serious form of skin cancer that, despite common fears, has an overall cure rate comparable to or better than many other cancers when diagnosed early. This comprehensive guide covers the clinical aspects and management of malignant melanoma, providing students with a clear understanding of its diagnosis, staging, and treatment.

What is Malignant Melanoma?

Malignant melanoma is a fascinating yet challenging disease, accounting for about 4% of all malignant neoplasms. While it causes significant patient fear due to perceived aggressive progression, its overall cure rate of 80% is favorable compared to many other cancers. Despite its lower incidence among skin cancers, melanoma is responsible for over 77% of skin cancer deaths.

The incidence of melanoma in the U.S. has been increasing faster than any other cancer. Current estimates suggest a lifetime risk of 1 in 37 for white men and 1 in 56 for white women. Understanding its molecular basis is improving, but successful treatment still relies heavily on surgical intervention.

Recognizing Malignant Melanoma: Clinical Aspects and Diagnosis

An experienced clinician can often diagnose malignant melanoma by its appearance, but a definitive diagnosis requires histologic analysis. It's crucial to differentiate melanoma from other pigmented lesions.

Common Pigmented Lesions

• Junctional Nevus: Small, flat, smooth, nonpalpable, light to dark brown or black lesions with nevus cells at the epidermis-dermis interface. They mature into intradermal nevi.
• Compound Nevus: Central portion elevates and thickens as nevus cells push into the dermis, while the periphery remains flat and junctional.
• Intradermal Nevus: Common adult mole, elevated due to nevus maturation and proliferation in the dermis, pushing up the epidermis.
• Blue Nevus: Appears blue because melanin is located deeper in the dermis, reflecting blue wavelengths of light.
• Congenital Nevus: Present at birth with pigment. Controversy exists regarding their malignant transformation, with reported rates from 2–42%. Large congenital nevi (>40 cm diameter) carry the highest risk of developing melanoma. Removal before adolescence is often recommended if feasible.

Atypical (Dysplastic) Nevus

An atypical nevus is a clinical diagnosis for a nevus with features suggestive of malignancy: large (>6 mm), macular surface, irregular margin, variegated color, and often a background of erythema. Histologically, these are called dysplastic nevi, characterized by melanocytic hyperplasia with nuclear atypia and architectural disorder.

Patients with dysplastic nevi are considered at greater risk for transformation to melanoma. The B-K mole syndrome describes atypical nevi in association with familial melanoma, suggesting a genetic basis for the tendency to develop these moles.

Differentiating Melanoma from Other Lesions

Clinicians must differentiate melanoma from benign lesions like seborrheic keratosis, pyogenic granuloma, and pigmented basal cell carcinoma. Microscopic examination is essential for proper diagnosis, as clinical impressions alone are not always accurate.

The ABCDE Criteria for Melanoma Detection

The American Cancer Society promotes the ABCD Guidelines for identifying suspicious pigmented lesions:

• Asymmetry of the lesion shape.
• Border irregularity, due to uneven growth rates.
• Color changes, representing pigment granules at varying depths.
• Diameter greater than 6 mm (1/4 inch).
• Evolving changes: Emphasizes the significance of changes in size, shape, symptoms (itching, tenderness), surface (especially bleeding), and shades of color. This is especially important for smaller melanomas.

Depigmentation within a lesion can occur due to immunologic regression, but it does not always indicate melanoma, as seen in a benign halo nevus. Dermatologists also often rely on the