Lipoma
From Felipedia
Benign lipoma is a tumor of adipose tissue, perhaps more accurately characterized as hamartoma. Older, neutered male, Siamese cats are predisposed, and tumors are most commonly found on the ventral abdomen. Obesity does not appear to be a factor in the development of lipomas in cats. In cats, >5% are multiple. In general, these tumors float when placed in formalin. Many lipomas merge imperceptibly with the adjacent non-neoplastic adipose tissue, making it difficult to determine when the entire lesion is excised. Lipomas with an abundant connective tissue stroma (fibrolipomas), cartilaginous stroma (chondrolipomas), or a prominent vascular component (angiolipomas) are also recognized. The cause of lipoma is thought to be due to chronic irritation of fat cells (lipocytes) from chemicals from dietary or insecticidal origin. Despite their benign nature, lipomas should not be ignored because they tend to enlarge over time, and their gross presentation may be indistinguishable from that of infiltrative lipomas or liposarcomas. Excision is usually curative.
Infiltrative lipoma (intra- and intermuscular lipoma) is a rare variant of benign lipoma found infrequently in cats. Infiltrative lipoma tend to dissect along fascial planes and between skeletal muscle bundles, are considered sarcomas of intermediate malignancy. They rarely metastasize. Aggressive excision is recommended, and amputation may be necessary.
Liposarcoma is more rare variant of infiltrative lipoma which occur in all domestic animals, including cats. In cats, feline leukaemia virus infection has been infrequently associated with their development; whether this is a coincidence or such infections play a causative role remains undefined. Liposarcomas are nodular and soft to firm. They may exude a mucinous fluid when sectioned. Many have palpable, partially encapsulated areas, but these zones should not be construed as evidence of a benign tumour. Liposarcomas are malignant neoplasms that have a low metastatic potential but are frequently pseudoencapsulated. Wide excision is recommended. Recurrence is common, so follow-up radiation therapy is indicated in cases with insufficient margins [1].
