[130] GATA-3 Is Helpful in Differentiating Primary Mammary Neuroendocrine Carcinomas from Metastatic Neuroendocrine Tumors

Shefali Chopra, Stacey Kim, Shikha Bose, Richard Mertens, Deepti Dhall. Cedars-Sinai Medical Center, Los Angeles, CA

Background: Metastatic neuroendocrine tumors in the breast (mNETs) can show histologic as well as immunohistochemical overlap with primary mammary carcinomas showing neuroendocrine differentiation (MC-NEs). Since the management of these tumors is quite different, it is of utmost importance to classify them accurately. GATA-3 is a transcription factor expressed by the luminal epithelial cells in the breast and is closely associated with estrogen receptor α in breast carcinoma. This study investigates the utility of GATA-3 in differentiating mNETs from MC-NEs.
Design: The anatomic pathology files of our institution were searched for MC-NEs and mNETs. Tissue blocks were available for 14 MC-NEs and 5 mNETs. In addition, 11 pancreatic, 8 ileal, and 12 pulmonary primary NETs were selected. GATA-3 immunohistochemistry was performed on all cases. The H&E slides, previously performed immunohistochemical studies, and medical records were extensively reviewed to confirm the primary site.
Results: The mean age of patients with MC-NEs and mNETs was 63 and 55, respectively. Four of 5 mNETs were from ileum and 1 was from ovary. The histologic appearance of MC-NEs and mNETs were quite similar, both showing neuroendocrine features. All mNETs were strongly and diffusely positive for synatophysin and chromogranin, whereas variable positivity for synaptophysin and chromogranin was noted in MC-NEs. All 14 (100%) MC-NEs stained strongly and diffusely for GATA-3, whereas all 5 mNETs and all 31 primary NETs of other sites were negative. All GATA-3 positive cases were moderately to strongly positive for ER. One of the mNETs that displayed weak ER positivity was negative for GATA-3. The immunohistochemical results are tabulated in Table 1.

Immunohistochemical staining pattern of MC-NEs and mNETs
 Diffuse and strong positivity for synaptophysin and/or chromograninPositivity for ERPositivity for GATA-3
Primary mammary carcinomas with NE differentiation10/14 (71%)14/14 (100%)14/14 (100%)
Metastatic neuroendocrine tumors5/5 (100%)1/5 (20%)0/5 (0%)

Conclusions: Metastatic NETs in the breast closely mimic primary breast carcinomas with neuroendocrine differentiation. GATA-3 and ER are helpful in distinguishing the two entities.
Category: Breast

Tuesday, March 5, 2013 1:00 PM

Poster Session IV # 61, Tuesday Afternoon


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