Track: Case Reports

Abstract:

Radiation-induced angiosarcomas of the breast are rare malignancies that carry a poor prognosis. Expected immunohistochemical profiles reflect vascular differentiation: CD31 and ERG positivity, with variable CD34 positivity. Expression of cytokeratins can be seen in epithelioid variants. GATA-3 is a transcription factor important for mammary gland development, playing a role in ductal epithelial cell differentiation. It serves as an important immunohistochemical marker of breast-origin carcinomas. We report a case of an 83-year-old female with breast radiation-induced angiosarcoma which displayed diffuse GATA-3 positivity, which has not been previously reported in the literature. The patient had a history of inflammatory carcinoma of the left breast (histologically a high-grade invasive ductal carcinoma of no special type) treated with lumpectomy and radiation therapy. 10 years later, she presented with skin thickening and three tender nodules (ranging from 0.6 cm to 2 cm) confined to the left breast skin. Biopsy showed a high-grade, epithelioid dermal neoplasm with abundant hemorrhage. The tumor was diffusely positive for GATA-3, CD31, and ERG, with focal CD34 positivity. Strong and diffuse MYC positivity with an increased Ki-67 proliferative index was also demonstrated. CK5/6, AE1/AE3, MOC-31, CK7, ER, PR, S100, Melan-A, and synaptophysin were all negative. The histopathologic features and immunohistochemical profile were consistent with radiation-induced angiosarcoma. With this case we highlight an unusual GATA-3 positive staining pattern in radiation-induced angiosarcoma of the breast which has not been previously documented. Awareness of this potential staining pitfall is essential for arriving at the correct diagnosis.

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Vicki Mercado-Evans