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Abstract

Angiosarcoma is a rare and highly aggressive malignant neoplasm usually characterized by atypical endothelial cells lining infiltrative vascular structures; however, vasoformation may lack in epithelioid variant. A rare pseudolymphomatous variant has been described, characterized by a dense inflammatory background mimicking a lymphoid neoplasm. We report a case of a 72-year-old woman with a previous history of left breast cancer and radiation therapy four years prior to developing erythematous skin thickening on her inferolateral left breast and a clinical suspicion of recurrent carcinoma vs angiosarcoma. Biopsy showed rare dyscohesive, pleomorphic large cells with nuclear hyperchromasia and prominent nucleoli, scattered within a dense inflammatory infiltrate of lymphocytes, histiocytes, plasma cells and scattered eosinophils involving superficial to mid dermis. No atypical vascular structures were noted. The atypical cells expressed CD30 and were negative for CD34, CD31, T- and B-cell markers in an initial work-up, raising suspicion for a CD30+ lymphoproliferative disease (LPD) of null cell type. Additional studies demonstrated that the large cells expressed other vascular markers including ERG and D2-40, which along with c-Myc confirmed the diagnosis of radiation-induced pseudolymphomatous angiosarcoma. This case is unique in that the diagnostic challenges posed by the dense lymphocytic infiltrate, paucity of neoplastic cells and lack of vasoformation are compounded by the abnormal phenotype including CD30 expression and lack of labeling with two widely used endothelial markers suggesting a CD30+ LPD. A broad IHC panel to confirm endothelial lineage and accurate diagnosis is recommended in this clinical context.