Gata3 Immunohistochemical Staining is A Useful Marker for Metastatic Breast Carcinoma in Fine Needle Aspiration Specimens

AIMS: The utility of GATA3 immunohistochemistry (IHC) as an aid to the cytological diagnosis of metastatic breast carcinoma in fine needle aspiration (FNA) specimens was investigated. MATERIALS AND METHODS: Cell block sections from 111 FNA cases of metastatic malignancy were stained for GATA3, including metastases from 43 breast and 44 nonmammary adenocarcinomas, 19 melanomas, 4 urothelial carcinomas, and 1 thyroid medullary carcinoma. Sites sampled included lymph nodes (87), bone (8), liver (5), lung (6), superficial masses (4), and pelvic mass (1). RESULTS: Ninety-one percent (39/43) of metastatic breast carcinoma cases were positive for GATA3. All estrogen receptor (ER)-positive were also GATA3 positive cases. The majority (9/14; 64%) of ER-negative and 37% (3/8) of triple-negative cases were positive for GATA3. All nonmammary adenocarcinoma cases were negative with the exception of one case of metastatic pancreatic adenocarcinoma. Metastatic melanoma cases were all negative but 75% (3/4) urothelial carcinomas expressed GATA3. CONCLUSIONS: GATA3 IHC staining is a useful addition to IHC panels for FNA samples in specific settings such as distinguishing metastatic breast from lung carcinoma or melanoma.