title: Specification and use of a mouse monoclonal antibody raised against melanosomes for the histopathologic diagnosis of amelanotic malignant melanoma.
abstract: The positive reactivity and specificity of a mouse monoclonal antibody (MoAb) human melanosome-specific antigen (HMSA) 2 raised against the melanosomal protein with amelanotic malignant melanoma on routine paraffin sections is reported. MoAb HMSA-2 identified cytoplasmic antigen with the following specifications: (1) a sharp heterogeneous expression in melanoma cells (acral lentiginous melanoma [ALM], 11 of 14; superficial spreading melanoma [SSM], 13 of 14; nodular melanoma [NM], one of three; and lentigo maligna melanoma [LMM], zero of two), whereas a diffuse homogeneous expression in cells of benign pigmented melanocytic nevi; and (2) an intense expression on amelanotic melanoma cells as opposed to a weak or negative expression on highly melanotic cells. The positive reactivity of MoAb HMSA-2 with amelanotic melanomas was exemplified by two shave-biopsy specimens of amelanotic subungual and plantar lesions, and by two cases of axillary and cervical amelanotic nodes that were left undiagnosed on routine hematoxylin and eosin (H & E) sections because of lack of melanin pigments. These were found, after diagnosis with MoAb HMSA-2, to possess the regressed primary lesions (both ALM).
mesh_terms: D000911:Antibodies, Monoclonal; D006801:Humans; D007124:Immunoenzyme Techniques; D008544:Melanocytes / Q000276:immunology*; D008545:Melanoma / Q000175:diagnosis*; D009362:Neoplasm Metastasis; D009508:Nevus, Pigmented / Q000276:immunology; D010232:Paraffin; D012878:Skin Neoplasms / Q000175:diagnosis*
chemical_list: D000911:Antibodies, Monoclonal; D010232:Paraffin