Epithelioid Angiosarcoma: A Diagnostic Dilemma with Clinically and Histopathologically Overlapping Features

Cutaneous angiosarcoma is a rare malignancy of endothelial cell origin that commonly presents in the head and neck region of elderly individuals and is known for high rates of lymph node metastasis and mortality. There is significant variability in the histopathologic features, and immunohistochemistry is necessary to help differentiate epithelioid angiosarcoma from lesions it may clinically mimic. Here, we report a rare case of poorly differentiated epithelioid angiosarcoma on the trunk initially diagnosed as poorly differentiated squamous cell carcinoma (SCC) on shave biopsy. A 56-year-old man presented for a full-body skin examination significant for a 5.6 x 2.8 mm brown-black macule on the left superomedial posterior trunk and a 5.0 x 2.7 mm pink, ulcerated papule on the right inferior posterior trunk. On histopathology, one lesion was found to be melanoma in situ, and the other showed ulcerated and infiltrative, poorly differentiated SCC. Post-excision histologic analysis of the right inferior back lesion revealed tumor cells immunoreactive to vimentin, ERG, and CD31 (PECAM-1). These findings suggested that the lesion previously diagnosed as SCC was an invasive, poorly differentiated epithelioid angiosarcoma. The patient underwent 40 sessions of radiotherapy. Epithelioid angiosarcoma occurring outside of the conventional epidemiologic profile is believed to portend higher mortality rates. This case highlights the importance of thorough clinical evaluation and appropriate histopathologic diagnosis of an aggressive neoplasm unlikely to present in this location. Further studies are required to explore potential risk factors, effective treatments, and long-term outcomes in patients with epithelioid angiosarcoma.