title: Melan-A/Mart-1 expression in various melanocytic lesions and in non-melanocytic soft tissue tumours.
abstract: OBJECTIVE
  The purpose of this study was to test different malignant non-melanocytic tumours with the commercially available antibody Melan-A to examine its diagnostic specificity and to compare the S100, Melan-A and HMB-45 reactivity in various melanocytic lesions.
  
  
  RESULTS
  Seventy-three benign and malignant melanocytic lesions and 31 cases of non-melanocytic tumours, sarcomas, carcinomas and carcinoids, were selected. Immunohistochemical staining of paraffin sections, following a high temperature antigen unmasking technique, was performed. Melan-A stains junctional and dermal melanocytes in all benign melanocytic lesions with the exception of neuro-naevoid areas. The epithelioid and the spindle cells in malignant melanomas did not show considerable difference in their Melan-A reactivity. The predominantly spindle cell type mucosal melanomas contained more Melan-A-positive cells than HMB-45-positive cells and similar results were observed in metastatic malignant melanomas. In desmoplastic melanomas the positivity of Melan-A was not consistent. None of the sarcomas, carcinomas and carcinoids expressed Melan-A. Almost all soft tissue tumours, except for two malignant gastrointestinal stromal tumours, were unreactive for HMB-45. These two cases did not react with Melan-A antibody.
  
  
  CONCLUSIONS
  Melan-A is a useful additional marker to differentiate non-melanocytic tumours from primary or metastatic melanoma. In melanocytic lesions the Melan-A staining pattern is similar to S100, but seems to be more specific. In desmoplastic melanomas, however, the variable Melan-A staining further necessitated detailed histological examination and the use of the S100 reaction.
authors.affiliation: Department of Human and Experimental Tumour Pathology, National Institute of Oncology, Hungary.
authors.forename: Z
authors.initials: Z
authors.lastname: Orosz
mesh_terms: D000951:Antigens, Neoplasm / Q000096:biosynthesis; D014408:Biomarkers, Tumor; D002276:Carcinoid Tumor / Q000378:metabolism*; D002277:Carcinoma / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D058965:MART-1 Antigen; D008545:Melanoma / Q000378:metabolism*; D058950:Melanoma-Specific Antigens; D009363:Neoplasm Proteins / Q000096:biosynthesis*; D009418:S100 Proteins / Q000096:biosynthesis; D012509:Sarcoma / Q000378:metabolism*; D012878:Skin Neoplasms / Q000378:metabolism*; D012983:Soft Tissue Neoplasms / Q000378:metabolism*
chemical_list: D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; D058965:MART-1 Antigen; C548667:MLANA protein, human; D058950:Melanoma-Specific Antigens; D009363:Neoplasm Proteins; D009418:S100 Proteins