Cellular Angiolipoma in the Breast: A Case Report and Literature Review of Its Pathogenesis

Angiolipoma is a benign variant of lipoma characterized by vascular proliferation among mature adipocytes, most commonly found on the extremities of young males. Cellular angiolipoma of the breast is extremely rare, with fewer than five cases reported in the English literature. We present a case of cellular angiolipoma in a 72-year-old female, manifesting as a 0.7 × 0.7 × 0.4 cm hyperechoic mass on ultrasound. Histopathological examination revealed a predominantly cellular lesion (~90%) interspersed with mature adipose tissue and abundant fibrin thrombi within small capillaries. The cellular component comprised spindle cells and vascular clusters with bland nuclei and low mitotic activity. Periodic acid-Schiff (PAS) staining and human herpesvirus 8 (HHV8) immunohistochemistry were negative. A diagnosis of benign cellular angiolipoma of the breast was made, with the tumor superficially involving the subcutaneous layer. The patient recovered uneventfully post-procedure. This report also discusses the pathophysiology and possible mechanisms underlying the development of angiolipoma.