title: S100, HMB-45, and Melan-A negative primary melanoma.
abstract: The diagnosis of malignant melanoma can be challenging given the wide variation in morphologic features and immunohistochemical stains are often used to confirm the diagnosis. We report a case of melanoma with loss of staining for S100 protein, HMB-45, and Melan-A, with retained expression of tyrosinase. Regional lymph node metastases showed positive S100 protein staining. Although the loss of phenotypic markers including S100 protein has been reported in metastatic melanoma, loss of S100 in primary melanoma is rare. Discordant staining between primary and metastatic lesions further emphasizes the protean nature of melanoma.
authors.affiliation: University of Washington Division of Dermatology, University of Washington, Seattle, Washington, USA. mshinoha@u.washington.edu
authors.forename: Michi M
authors.initials: MM
authors.lastname: Shinohara
authors.forename: Heike
authors.initials: H
authors.lastname: Deubner
authors.forename: Zsolt B
authors.initials: ZB
authors.lastname: Argenyi
mesh_terms: D015703:Antigens, CD / Q000032:analysis; D015214:Antigens, Differentiation, Myelomonocytic / Q000032:analysis; D000951:Antigens, Neoplasm / Q000032:analysis*; D000970:Antineoplastic Agents / Q000627:therapeutic use; D014408:Biomarkers, Tumor / Q000032:analysis*; D003131:Combined Modality Therapy; D005153:Facial Neoplasms / Q000737:chemistry* / Q000175:diagnosis / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery; D017809:Fatal Outcome; D006801:Humans; D008207:Lymphatic Metastasis; D058965:MART-1 Antigen; D008297:Male; D008545:Melanoma / Q000737:chemistry* / Q000175:diagnosis / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery; D058950:Melanoma-Specific Antigens; D008875:Middle Aged; D014442:Monophenol Monooxygenase / Q000032:analysis; D009363:Neoplasm Proteins / Q000032:analysis*; D010166:Palliative Care; D009418:S100 Proteins / Q000032:analysis*; D012782:Shoulder; D012878:Skin Neoplasms / Q000737:chemistry* / Q000175:diagnosis / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery; D000097382:CD68 Molecule
chemical_list: D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D000951:Antigens, Neoplasm; D000970:Antineoplastic Agents; D014408:Biomarkers, Tumor; D058965:MART-1 Antigen; D058950:Melanoma-Specific Antigens; D014442:Monophenol Monooxygenase; D009363:Neoplasm Proteins; D009418:S100 Proteins; C067980:CD68 antigen, human; D000097382:CD68 Molecule; C548667:MLANA protein, human