Free-floating fat in a furry! A mobile necrotic lipoma in the abdomen of a guinea pig

Publication date 1st April 2019
Authors C Webb


To report a mobile intra-abdominal necrotic lipoma in a male guinea pig.


An adult male neutered guinea pig (age approximately 3 years) was presented for routine health check after being adopted. Recent history was unremarkable though physical examination revealed an incidental non-painful, firm, highly mobile, bi-convex mass in the mid abdomen. Repeat examination 2 months later revealed no palpable changes to the mass, though investigation was sought as he had become less interactive. Ultrasound examination revealed an approximately 60mm x 40mm mass with heterogenous architecture and a thin hyperechoic rim. A detached, ovoid, brown, irregular mass with a thin friable exterior was identified and removed via a midline laparotomy without the need for ligation.


Histopathological examination revealed the mass was almost entirely composed of necrotic adipose tissue. Adipocytes were well differentiated and the necrotic outlines of the cells were retained. Multifocal areas of necrotic fibrous connective tissue and necrotic debris admixed with degenerate neutrophils were noted. Multi-focally, small to moderate amounts of mineralised material was present. The mass was surrounded by a thin rim of fibrous connective tissue and diagnosed as a necrotic lipoma.


Several reports of intra-abdominal mobile encapsulated adipose tissue in cows have been described with comparisons being made to those found in the subcutis of extremities in humans. To the authors knowledge this is the first case of a free-floating necrotic lipoma in the coelomic cavity of a guinea pig.