Angiolipoma retroperitoneal infiltrante de los músculos psoas e ilíaco

Angiolipomas are benign tumours composed of variable proportions of blood vessels and mature adipocytes. There are two histologically distinct types of angiolipomas: infiltrating and non-infiltrating, and which differ with respect to gender-related incidence, age at presentation, site, anatomo-pathology and aggressiveness. They occur, mostly, as multiple encapsulated nodules that are small in size, painful, but rarely infiltrating. We present a case report of a giant infiltrating angiolipoma located in the retro-peritoneum, and whose clinical manifestations were related to compression of neighbouring structures. Being retro-peritoneal, the psoas and iliac muscles were affected. Despite resection with free borders, there was a relapse two years later. This necessitated a further, more radical resection.