Angiolipoma : Microscopic Features

Angiolipoma is a benign lipomatous tumor that usually presents as multiple, small, painful/tender subcutaneous nodules on the forearm, arm or trunk of young adults with a male predominance. Rare sites include oral cavity, intra-articular, extradural, and bronchial. About 5% cases are familial with an autosomal dominant inheritance.Most angiolipomas have a normal karyotype but show mutations in PRKD2 gene which plays an important role in angiogenesis.Grossly, they are circumscribed encapsulated yellow masses with a reddish tinge, usually measuring < 2 cm in size. They are composed of mature adipose tissue separated by a network of capillary-caliber blood vessels often containing fibrin thrombi. The lining endothelium lacks atypia. Cases with abundant adipose tissue resemble ordinary lipomas. Tumors with a prominent vascular component are called cellular angiolipomas.The differential diagnosis includes ordinary lipoma, capillary hemangioma, intramuscular hemangioma, Kaposi sarcoma and angiosarcoma. Simple resection is curative. There is no risk of recurrence or malignant transformation.