title: Primary cutaneous signet-ring cell melanoma: a clinico-pathologic and immunohistochemical study of two cases.
abstract: Signet-ring cell malignant melanoma is a rare histopathologic variant of malignant melanoma with only a few described cases. We report the clinical, histopathological, and immunohistochemical features of two cases of primary cutaneous signet-ring cell malignant melanoma. Neoplastic melanocytes showed abundant clear cytoplasm compressing the nuclei to the periphery, sometimes resulting in a signet-ring appearance. Immunohistochemically, neoplastic melanocytes in both cases expressed immunoreactivity for the usual melanocytic markers S-100 protein and Melan-A, although only the second case resulted HMB-45 positive. We review the literature about this rare cytologic variant of malignant melanoma and discuss the differential diagnosis with other cutaneous neoplasms that may show a signet-ring cell appearance of their neoplastic cells.
mesh_terms: D000368:Aged; D014408:Biomarkers, Tumor / Q000032:analysis; D018279:Carcinoma, Signet Ring Cell / Q000175:diagnosis; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008544:Melanocytes / Q000737:chemistry / Q000473:pathology*; D008545:Melanoma / Q000737:chemistry / Q000473:pathology* / Q000601:surgery; D008875:Middle Aged; D012878:Skin Neoplasms / Q000737:chemistry / Q000473:pathology* / Q000601:surgery; D016896:Treatment Outcome
chemical_list: D014408:Biomarkers, Tumor