Lipoma are a relatively slow-growing neoplasia of canine cutaneous fat and subcutaneous muscle.
Although lipomas primarily involve fat cells, variants have been reported which are characterized by an additional component such as capillaries (angiolipomas) or fibrous connective tissue (fibrolipomas, chondrolipoma), thymus (thymofibrolipoma) and bone (osteolipoma).
These tumors are rarely metastatic but can invade intermuscular sites. They commonly occur on the trunk, although aberrant locations include the epiglottis, peritoneum, orbit and pericardium have been reported. Large lipomas may become centrally necrotic and result in toxemia. Infiltration of regional bone, particular of the vertebrae can result in neurological disease due to spinal compression.
Clinically, these tumors vary in size from small pedunculated subcutaneous swellings to large solitary tumors weighing up to 1 kg or more. They are commonly diagnosed in dogs over 10 years of age. Lameness may occur if the tumor infiltrates digital tendons of the limbs.
The causes of this tumor are multivariate, including:
- Exposure to various dietary and environmental toxins
- Breed predisposition
Diagnosis is readily established by the location, shape and relatively benign nature of the mass, supported by histological examination of needle-biopsy or exploratory sampling.
Surgical excision is usually curative. Liposuction is an alternative surgical method, though more technically demanding and not recommended for infiltrative or giant inguinal lipomas.
Small tumor are often left untreated unless they interfere with critical organs or are aesthetically unpleasing to the owner. They are rarely life-threatening.
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