Melanoma metastatic to the breast: utility of fine needle aspiration and immunohistochemistry.
OBJECTIVE
To describe the morphologic spectrum of metastatic malignant melanoma (MM) cells involving the breast and to explore the diagnostic utility of HMB45, Mart-1, Melan-A and T311 (antityrosinase) antibodies in fine needle aspiration material of MM metastatic to the breast.


METHODS
Cytologic material from 21 cases (18 women) was reviewed for cytomorphology (epithelioid, spindled, mixed) and immunocytochemical staining attributes for Mart-1, HMB45, T311, Melan-A and cytokeratin based on tissue availability.


RESULTS
Seventeen cases (81%) demonstrated epithelioid cell morphology, with 14% exhibiting mixed and 5% spindled morphologies. All 21 cases (100%) were immunoreactive with Mart-1 antibody, with 81% (17/21) immunoreactive for HMB45. In 38% of cases there was a similar percentage of cells immunoreactive for Mart-1 and HMB45, while 48% showed a higher percentage of cells immunoreactive for MART-1 than HMB45. Immunoreactivity with T311 was seen in 8 of 11 cases tested (73%). All six cases tested (100%) were immunoreactive with Melan-A. Staining for cytokeratin was negative in all eight cases tested.


CONCLUSIONS
Because the majority of MM metastatic to the breast shows epithelioid cell morphology, it may mimic primary breast carcinoma. Mart-1 should be part of the immunocytochemical panel utilized to confirm the diagnosis of MM metastatic to the breast.
Filie
Armando Carlos
AC
Cytopathology Section, Laboratory of Pathology, National Cancer Institute, Bethesda, Maryland, USA.
Simsir
Aylin
A
Fetsch
Patricia
P
Abati
Andrea
A
D000328:Adult; D000368:Aged; D000951:Antigens, Neoplasm / Q000378:metabolism; D015415:Biomarkers; D001707:Biopsy, Needle; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology* / Q000556:secondary*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007633:Keratins / Q000378:metabolism; D058965:MART-1 Antigen; D008545:Melanoma / Q000378:metabolism / Q000473:pathology* / Q000556:secondary*; D058950:Melanoma-Specific Antigens; D008875:Middle Aged; D014442:Monophenol Monooxygenase / Q000378:metabolism; D009363:Neoplasm Proteins / Q000378:metabolism; D012878:Skin Neoplasms / Q000473:pathology
D000951:Antigens, Neoplasm; D015415:Biomarkers; D058965:MART-1 Antigen; C548667:MLANA protein, human; D058950:Melanoma-Specific Antigens; D009363:Neoplasm Proteins; D007633:Keratins; D014442:Monophenol Monooxygenase