Melan-A as a useful diagnostic immunohistochemical stain for the diagnosis of primary sinonasal melanomas.
BACKGROUND
Sinonasal melanomas are rare neoplasms whose diagnosis may require confirmatory immunohistochemical stains. S-100 protein and HMB-45, the stains most commonly used, have varying sensitivities and specificities. Melan-A, a more recent melanoma-specific marker, may prove helpful when S-100 protein and HMB-45 stains are negative or equivocal.


METHODS
Seven cases of sinonasal melanoma were assessed for reactivity with Melan-A, S-100 protein and HMB-45.


RESULTS
The study group consisted of two women and five men ages 40 to 83. Six of the neoplasms were strongly positive for S-100 protein. One case was negative for S-100 protein and HMB-45 but positive for Melan-A. HMB-45 staining varied between diffusely positive (three cases), focally positive (two cases), and negative (two cases). All cases were positive for Melan-A either diffusely (four cases) or focally (three cases).


CONCLUSIONS
Because Melan-A can be positive in cases that are S-100 protein or HMB-45 negative, it is a useful component in the immunohistochemical panel for the diagnosis of sinonasal melanomas.
Snyder
Matthew L
ML
Department of Pathology, University of Michigan Hospitals, 1500 East Medical Center Drive, Room 2G332, Ann Arbor, MI 48109, USA.
Paulino
Augusto F G
AF
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000951:Antigens, Neoplasm; D001707:Biopsy, Needle; D046508:Culture Techniques; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D058965:MART-1 Antigen; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008545:Melanoma / Q000175:diagnosis / Q000473:pathology*; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000032:analysis*; D010255:Paranasal Sinus Neoplasms / Q000473:pathology*; D012494:Sampling Studies; D012680:Sensitivity and Specificity; D013194:Staining and Labeling
D000951:Antigens, Neoplasm; D058965:MART-1 Antigen; C548667:MLANA protein, human; D009363:Neoplasm Proteins