Abstract

Background: Melanoma contributes to 70-80% of skin cancer-related deaths. Early detection and accurate diagnosis are critical to patient survival; however, unusual presentations continue to pose challenges for clinicians and pathologists. Many of these cases are forwarded for expert review and critical teaching points are highlighted. Objectives: To elucidate the distinction between primary melanoma and epidermotropic metastases, and report potential pitfalls and worrisome features in lesions not otherwise meeting diagnostic criteria for melanoma, using 4 challenging cases: a 37-year-old with a melanoma showing irregular morphology reviewed to be a deep-penetrating-nevus-like melanoma; an 84-year-old with an unclassifiable melanoma reviewed to be a melanoma intermixed with an intradermal melanocytic nevus supporting primary origin; a 69-year-old with multiple recurring lesions over the same limb reviewed to confirm epidermotropic metastases and satellitosis; and lastly a 47-year-old with synchronous presentation of lesions at different body sites all including an intraepidermal component. Conclusions: Pathologists should be aware of distinct histological clues of various types of primary cutaneous melanoma and epidermotropic metastases.

Financial Disclosure:
No current or relevant financial relationships exist.