Primary cutaneous angiosarcoma of the scalp initially misdiagnosed as cellulitis in a 95-year-old Asian man: A case report.

Cutaneous angiosarcoma is a rare and aggressive malignant vascular tumor that most commonly affects the scalp and face of elderly individuals. Because its early clinical manifestations are often non-specific, it may be misdiagnosed as a benign inflammatory or infectious disorder, resulting in delayed diagnosis and treatment. The case of a 95-year-old Asian man is reported, who presented with a 5-month history of a progressively enlarging scalp lesion that had initially been diagnosed as cellulitis and treated with antibiotics without improvement. Physical examination revealed a 4×5 cm ill-defined violaceous infiltrative plaque with central ulceration on the scalp. Histopathological examination demonstrated irregular anastomosing vascular channels lined by mildly atypical endothelial cells infiltrating the dermis and subcutis. Immunohistochemical staining was positive for CD31, CD34 and erythroblast transformation-specific related gene, with a Ki-67 index of ~20%; C-MYC staining showed weak focal positivity in ~10% of the lesional cells, whereas cytokeratin and epithelial membrane antigen staining were negative. Additional immunohistochemical staining demonstrated negative human herpesvirus 8 staining and the absence of a continuous smooth muscle actin-positive pericytic layer around the neoplastic vascular channels. Imaging studies showed no evidence of regional or distant metastasis. The patient subsequently underwent wide local excision with a 2 cm gross peripheral margin to the level of the galea aponeurotica. Intraoperative frozen-section and final permanent-section examinations confirmed tumor-free surgical margins. Adjuvant radiotherapy was not administered because of the advanced age of the patient and complete excision with negative margins. At the 8-month postoperative follow-up, clinical examination showed no evidence of local recurrence. The present case highlights that primary cutaneous angiosarcoma of the scalp may closely mimic cellulitis in its early stage, particularly in elderly patients, and that a progressive violaceous scalp lesion unresponsive to conventional antibiotic therapy should prompt early biopsy and histopathological evaluation.