Histopathology of melanoma

From specimen to diagnosis

After a biopsy, tissue is prepared as thin sections and stained. The pathologist assesses the cells, their distribution and their relationship to skin layers. A clinical photograph cannot provide this information.

Key terms to understand

In situ or invasive

Whether cells are confined to the epidermis or invade underlying tissue.

Thickness and ulceration

Important features for staging invasive melanoma.

Margins

The relationship between the lesion and the edges of the removed specimen.

Other findings

May include mitoses, microsatellites and other case-specific features.

Additional stains and tests

In selected cases, immunohistochemistry helps identify the nature of the cells. Markers are interpreted together; none should be read as a stand-alone “positive or negative for melanoma” home test. Additional tests may be requested to clarify difficult cases.

Discussing the report

Ask your doctor to explain the diagnosis, margins and next steps. For an uncertain or complex case, specialist review of the slides may be helpful. Do not change follow-up or treatment based on one word in a report.