Malignant Melanoma

Melanoma is a malignant tumor of melanocytes. While less common in people with darker skin tones, it is often more lethal due to delayed diagnosis and more aggressive subtypes.

• The "Change" Narrative: Patients typically report a new or existing mole that has changed in size, shape, or color.

• Symptoms: While usually painless, advanced lesions may become itchy, tender, or prone to bleeding and ulceration.

• The Acral Presentation: In Black, Asian, and Hispanic patients, the history often involves a spot on the palms, soles of the feet, or a dark streak in the nail (subungual). These are often misdiagnosed by patients as "bruises" or "calluses" that fail to heal.

• Risk Factors: A history of atypical moles, a first-degree family history of melanoma, or a state of chronic immunosuppression.

• Prognosis Note: Late detection in acral locations is the primary reason for poorer outcomes in Black patients, as these areas are often overlooked during routine examinations.

The ABCDE rule remains the gold standard for clinical assessment:

• A – Asymmetry: One half of the lesion does not match the other.

• B – Border Irregularity: Edges are ragged, notched, or blurred.

• C – Color Variation: Multiple shades of brown, black, tan, or even red/blue within one lesion.

• D – Diameter: Usually >6 mm (about the size of a pencil eraser), though "small-diameter" melanomas exist.

• E – Evolving: Any change in size, shape, or symptoms over time.

Key Findings in Acral/Nail Locations:

• Acral Lentiginous Melanoma (ALM): Large, irregular, hyperpigmented patches on the palms or soles.

• Subungual Melanoma: A wide (typically >3 mm), dark, longitudinal band in the nail.

• Hutchinson’s Sign: Crucial sign. Pigmentation that extends from the nail plate onto the surrounding nail fold (cuticle). This is highly suggestive of melanoma.

Crucial Note for Darker Skin Tones

• Anatomic Distribution: While sun-exposed areas (face, back) are common in lighter skin, the majority of melanomas in Black patients (up to 75%) occur in non-sun-exposed acral sites (palms, soles, subungual).

• Late-Stage Presentation: Lesions are frequently detected only once they become ulcerated or nodular, which correlates with a higher "Breslow thickness" and worse survival rates.

• Differential Diagnosis:

  • Benign Acral Nevi: Very common; usually smaller, symmetrical, and follow the ridges of the skin (furrow pattern) on dermoscopy.

  • Longitudinal Melanonychia: Benign pigment streaks in the nails. These are very common in Black patients (often multiple nails); however, a single wide, changing band must be biopsied.

  • Tinea Nigra: A fungal infection causing a dark patch on the palm; unlike melanoma, it can be scraped off or treated with antifungals.

Management is stage-dependent and requires a multidisciplinary approach (Dermatology, Oncology, Surgery).

1. Surgical Excision (Primary Treatment): The definitive treatment is Wide Local Excision (WLE) with margins determined by the tumor's "Breslow thickness" (depth):

   • In situ (Stage 0): 0.5 cm – 1.0 cm margin.

   • Thickness <1 mm: 1 cm margin.

   • Thickness 1–2 mm: 1 cm – 2 cm margin.

   • Thickness >2 mm: 2 cm margin recommended.

   • Note: Acral locations may require specialized surgical techniques or, in advanced subungual cases, digital amputation.

2. Adjuvant Therapy (Advanced Stages): For patients with lymph node involvement or metastatic disease:

   • Immunotherapy (Checkpoint Inhibitors): * Pembrolizumab: 200 mg IV every 3 weeks (or 400 mg every 6 weeks).

     • Nivolumab: 240 mg IV every 2 weeks (or 480 mg every 4 weeks).

   • Targeted Therapy: Used if the tumor is BRAF V600 mutation-positive (common in sun-damaged skin, less common in ALM).

     • Dabrafenib (150 mg BID) + Trametinib (2 mg daily).

3. Prognosis and Complications:

   • Metastasis: Melanoma can spread rapidly via the lymphatic and hematogenous routes to the lungs, liver, and brain.

   • Follow-up: High-risk patients require full-body skin examinations every 3–6 months for the first 5 years.

Darker Skin Tones – Specific Treatment Risks:

• Acral Healing: Surgical sites on the soles of the feet are prone to slower healing and infection.

• Cosmetic Impact: Wide local excisions on the face or hands can lead to significant scarring or the need for skin grafts, which may result in "mismatched" skin color.

• Biopsy Urgency: If an acral lesion is suspicious, a punch or incisional biopsy must be performed through the thickest part of the lesion. Never "shave" a suspected acral melanoma, as it makes determining Breslow thickness impossible.

• DermNet NZ – Acral Lentiginous Melanoma: https://dermnetnz.org/topics/acral-lentiginous-melanoma

• StatPearls – Melanoma (2024 update): https://www.ncbi.nlm.nih.gov/books/NBK470409/

• Skin Cancer Foundation – Skin Cancer in People of Color.