Malignant melanoma with clinical and histologic features of Merkel cell carcinoma
Department of Medicine, Division of Dermatology
Medical Subject Headings
Antibodies, Monoclonal; Carcinoma, Merkel Cell; Cheek; Diagnosis, Differential; Humans; Male; Melanocytes; Melanoma; Microscopy, Electron; Middle Aged; S100 Proteins; Skin Neoplasms; Staining and Labeling
Dermatology | Neoplasms | Skin and Connective Tissue Diseases
We describe a patient with malignant melanoma that resembled a Merkel cell carcinoma both clinically and histologically. Immunohistochemical studies showed focally positive staining with S-100 protein and strongly positive staining with HMB-45. Ultrastructural study confirmed the diagnosis by demonstrating premelanosomes and melanosomes. Although the tumor appeared to be clinically unimpressive, it was a deep melanoma with a Breslow level of 3.8 mm that necessitated aggressive treatment. Small cell melanoma must be considered in the differential diagnosis of small cell tumors, which also includes lymphoma, eccrine carcinoma, squamous cell carcinoma, and Merkel cell carcinoma. The diagnosis of amelanotic melanoma, including the small cell variant, may require electron microscopic studies.
House, Nancy S.; Fedok, Fred G.; Maloney, Mary E.; and Helm, Klaus F., "Malignant melanoma with clinical and histologic features of Merkel cell carcinoma" (1994). Dermatology Publications and Presentations. 10.