Findings

Note the light pigmentation of this lesion with surface erosion.

Impression

Malignant melanoma

Pathology Pointer

Although uncommon, some cases of malignant melanoma may not be pigmented, despite the fact that they are composed of neoplastic melanocytes. In such a case, diagnosis requires immunohistochemical demonstration of marker substances, namely S100 (sensitive , but not specific) and / or HMB45 (specific - stains melanosome).

Preparation

Fresh

View

Clinical photograph

Specimen

Skin

Image Credit

Katsumi M. Miyai, M.D., Ph.D
Department of Pathology
School of Medicine
University of California, San Diego