Simulants of malignant melanoma

During the recent period, dermoscopy has yielded improvement inthe early disclosure of various atypical melanocytic neoplasms (AMN)of the skin. Beyond this clinical procedure, AMN histopathologyremains mandatory for establishing their precise diagnosis. Of note,panels of experts in AMN merely report moderate agreement in variouspuzzling cases. Divergences in opinion and misdiagnosis are likelyincreased when histopathological criteria are not fine-tuned andwhen facing a diversity of AMN types. Furthermore, some AMN havebeen differently named in the literature including atypical Spitz tumor,metastasizing Spitz tumor, borderline and intermediate melanocytictumor, malignant Spitz nevus, pigmented epithelioid melanocytoma oranimal-type melanoma. Some acronyms have been further suggestedsuch as MELTUMP (after melanocytic tumor of uncertain malignantpotential) and STUMP (after Spitzoid melanocytic tumor of uncertainmalignant potential). In this review, such AMN at the exclusion ofcutaneous malignant melanoma (MM) variants, are grouped under thetentative broad heading skin melanocytoma. Such set of AMN frequentlyfollows an indolent course, although they exhibit atypical andsometimes worrisome patterns or cytological atypia. Rare cases of skinmelanocytomas progress to loco regional clusters of lesions (agminatemelanocytomas), and even to regional lymph nodes. At times, the distinctionbetween a skin melanocytoma and MM remains puzzling.However, multipronged immunohistochemistry and emerging molecularbiology help profiling any malignancy risk if present.