B. Angiosarcoma
A nodular and interstitial infiltrative dermal proliferation composed of atypical vascular channels and intersecting fascicles of poorly differentiated spindle cells was noted on the biopsy results. Vascular channels dissected collagen bundles and were lined by atypical endothelium demonstrating nuclear hyperchromasia (Figure, B). Focal confluence and piling up of endothelial cells lining the vascular channels were also noted. On immunohistological examination, tumor components included CD31, with diffuse expression of FLI-1 and ERG in both the vascular and spindle cell tumor components. Tumor cells were negative for epithelial membrane antigen, cytokeratin 5/6, p63, S100 protein, SOX10, and CD10.
Angiosarcoma (AS) is a rare malignancy of endothelial origin that is classified into cutaneous, visceral, and soft-tissue subtypes.1 This neoplasm generally occurs in adults, with the highest incidence in the seventh decade of life.2 Angiosarcoma commonly affects the face, scalp, and neck, presenting asymptomatically as a hematomalike lesion; whereas advanced lesions can mimic other cutaneous neoplasms such as squamous cell carcinoma.3 Because AS has an initial nonspecific clinical presentation and clinical features similar to those of other cutaneous malignant neoplasms, diagnosis is often delayed.