Sarcomatous transformation in a cellular angiofibroma: a case report.

Cellular angiofibroma is a rare benign mesenchymal tumour of middle-aged adults. This tumour is usually located in the vulvovaginal or inguinoscrotal region. This report describes the case of a patient with a 3.5 cm subcutaneous mass, 2 cm below the left anterior superior iliac spine. Grossly, the mass had tan-white cut surface with a 1.5 cm tan-yellow, whorled, well-delineated nodule. Histologically, the tumour was composed primarily of cytologically bland spindle cells set in a collagenous stroma, with multiple dilated vessels. Other areas showed an abrupt transition to hypercellular sarcomatous elements, including pleomorphic cells with high mitotic activity. The tumour cells were diffusely positive for vimentin and factor XIIIa, and weakly positive for CD34. The patient did not develop any recurrences or metastases, and expired 3 years later of metastatic poorly differentiated carcinoma of unknown origin. This is believed to be the first reported case of sarcomatous transformation in a cellular angiofibroma.