Pulmonary Metastasis of a Postradiation Breast Epithelioid Angiosarcoma Mimicking Adenocarcinoma

BACKGROUND: Epithelioid angiosarcoma (EAS) is a mesenchymal neoplasm that may appear indistinguishable from carcinoma, melanoma and other tumors with epithelioid/epithelial differentiation. We report a case of metastatic postradiation EAS to the lungs that was mistaken for adenocarcinoma. CASE: A 45-year-old woman who received radiotherapy for ductal carcinoma in situ (DCIS) 5 years previously had a local recurrence a year earlier and recent development of bilateral small pulmonary nodules. Fine needle aspiration biopsy of the lung lesions showed round to oval tumor cells with amphophilic cytoplasm. An interpretation of adenocarcinoma was rendered during assessment for specimen adequacy. The original breast tumor was typical of cribriform DCIS. Review of the recurrent breast tumor (initially reported as DCIS) and a prior wedge resection of the lung nodules (reported as EAS) showed an epithelial-appearing tumor exhibiting an endothelial immunophenotype CONCLUSION: The cytologic features of EAS may resemble those of other neoplasms. In evaluating tumors with epithelioid morphology, mesenchymal tumors should also be considered so that appropriate antibodies can be included in the panel for immunohistochemistry. The importance of reviewing the patient's previous biopsy materials cannot be overemphasized.