Angiolipomatous tumors in dogs and a cat.

Variants of lipoma are uncommon, although fibrolipoma and infiltrative lipoma have been well documented. This report describes two cases of rare angiolipoma in dogs and the first documentation of angiofibrolipoma and infiltrating angiolipoma in a cat and a dog, respectively. Tumors were solitary, and most were located on the thorax of middle-aged patients. Angiolipomas were composed of mature adipose tissue mixed with variable numbers of blood vessels. In addition to the adipose and vascular components, the angiofibrolipoma contained bundles of collagenous connective tissue. The infiltrative angiolipoma had a primary mass external to the muscle and was histologically similar to a mixed intramuscular hemangioma that was confined to the muscle. Both disrupted bundles of striated muscle and were associated with segmental degeneration and loss of myofibers.