How should I evaluate and treat a patient with a new, changing pigmented skin lesion suspicious for melanoma?

Evaluation and Treatment of Suspected Melanoma

Initial Clinical Assessment

Any new or changing pigmented lesion should be evaluated using the ABCDE criteria combined with the "ugly duckling" concept, with dermoscopy by an experienced clinician to enhance diagnostic accuracy, followed by full-thickness excisional biopsy for any suspicious lesion. 1, 2

ABCDE Criteria for Lesion Evaluation

Apply these criteria systematically to every suspicious pigmented lesion:

• Asymmetry: One half of the lesion does not match the other half, present in approximately 65% of melanomas 2
• Border irregularity: Uneven, notched, or scalloped edges; regular borders are found in only 12% of melanomas 2
• Color variegation: Multiple colors or uneven pigmentation distribution within a single lesion 1, 2
• Diameter: While traditionally >6mm was the threshold, many primary melanomas today are <5mm, making this criterion unreliable 1, 2
• Evolution: Changes in colors, elevation, or size over time—this is the most critical criterion for rapidly growing amelanotic melanomas 2

Critical Diagnostic Pitfalls to Avoid

The ABCDE criteria have significant limitations that can lead to missed diagnoses:

• Nodular melanomas often present as symmetric, dome-shaped nodules with regular borders and uniform color, violating the traditional ABCDE criteria 2
• Nodular melanomas grow rapidly in elevation rather than diameter, making the "E" (evolution) criterion critical 2
• Approximately 38% of all melanomas are ≤6mm in diameter, violating the "D" criterion 2
• Amelanotic melanomas can present with minimal pigmentation, necessitating evaluation beyond color alone 3

The "Ugly Duckling" Concept

This approach is more valuable than ABCDE criteria for nodular and desmoplastic subtypes because nevi in the same individual tend to resemble one another, and melanomas often do not fit the individual nevus pattern 1, 2. This concept identifies lesions that stand out from the patient's overall nevus pattern 2.

Dermoscopy

Dermoscopy by an experienced physician enhances diagnostic accuracy beyond clinical examination alone 1, 4. However, it should only be performed by clinicians with proven expertise 3.

When to Biopsy

Maintain a low threshold for biopsy in these situations:

• Any rapidly growing nodular lesion, regardless of symmetry or border regularity 2
• Any documented change in size, shape, or color of a pigmented lesion mandates immediate excisional biopsy 3
• Any lesion that does not fit the patient's overall nevus pattern (ugly duckling) 2
• Any lesion meeting multiple ABCDE criteria 1, 2

Biopsy Technique

Full-thickness excisional biopsy with a 2mm peripheral margin is the standard of care for any lesion suspected of melanoma 1, 3, 4. This is mandatory because:

• Partial or shave biopsies may miss the most invasive component 3
• Complete histologic assessment including maximum Breslow thickness is required for staging 1, 3
• The Breslow depth is the most important prognostic parameter 5
• Frozen-section analysis should be avoided as it compromises diagnostic accuracy 3

Alternative biopsy methods (deep shave, punch) may be appropriate in certain anatomic locations, but the specimen must be adequate to determine histologic depth 5.

Histopathology Requirements

Processing by an experienced pathology institute is mandatory 1, 4. The histology report must include:

• Maximum thickness in millimeters (Breslow depth) 1, 4
• Mitotic rate 1
• Presence of ulceration 1, 4
• Presence and extent of regression 1, 4
• Clearance of surgical margins 1, 4
• Anatomical site 1
• Melanoma type (superficial spreading, nodular, lentigo maligna, acrolentiginous) 1
• Clark level of invasion 4

Differential Diagnosis Considerations

Be aware that several benign entities can mimic melanoma:

• Atypical (dysplastic) nevi may display some ABCDE features yet remain benign 3
• Pigmented basal cell carcinoma can be distinguished by characteristic dermatoscopic patterns 3
• Seborrheic keratosis is the most common benign mimic; experienced clinicians can reliably separate it using dermatoscopy 3
• Thrombosed or pigmented hemangiomas reveal vascular structures on dermatoscopy 3

Initial Staging After Diagnosis

Physical examination must assess for:

• Other suspicious pigmented lesions 1
• Tumor satellites and in-transit metastases 1
• Regional lymph node involvement 1
• Systemic metastases 1

For low-risk melanomas (pT1a), no additional investigations are necessary; in higher tumor stages, imaging is recommended for proper staging 1.

Surgical Treatment of Localized Disease

Wide excision with appropriate safety margins:

• In situ melanomas: 0.5 cm margins 1
• Breslow thickness up to 2mm: 1 cm margins 1
• Breslow thickness >2mm: 2 cm margins 1

Modifications may be needed for preservation of function in acral and facial melanomas 1.

Mutation Testing

Mutation analysis for BRAF and optionally NRAS and c-Kit is necessary only in cases of metastatic disease; mutational testing of primary tumors without metastases is not recommended 1. Testing must be performed in accredited institutes with careful quality controls 1.