HISTORY

A fourteen-year-old intact male Irish setter weighing 31 kg, was presented to the Murcia University Veterinary Teaching Hospital with an inguinal swelling of twelve months of duration, although in the last four months the swelling had grown. On clinical examination the dog appeared bright, alert and a large, non-painful caudal abdominal mass was palpated. The mass was causing right-sided deviation of the penis and prepuce. In addition, the presence of the mass in the left caudal flank and inguinal region required circumduction of the left pelvic limb during locomotion. Haematology and serum biochemistry values were within normal ranges. Abdominal radiography revealed a large fat-dense mass in the mid to caudal abdomen, displacing the intestines cranially and dorsally. Thoracic radiographs were unremarkable. Abdominal ultrasound confirmed the presence of a fat-echogenic mass. Cytological analysis of fine needle aspirate of the mass revealed adipose tissue. Surgical excision was performed generally by blunt dissection and digital extrusion. A 5.8 kg fatty mass was located under the muscle rectus abdominis and between the muscles of the internal abdominal oblique and transversus abdominis. There was no gross evidence of invasion into the muscles during surgical exploration. Histopathological examination revealed a simple lipoma. The dog made an uneventful recovery from surgery. Recurrence of the abdominal distension was not seen in a six-month follow-up period.

DISCUSSION

Intermuscular lipoma is a rare variant of simple lipoma and has been previously reported in the dog. The tumour was situated in the caudal thigh region of dogs, predominantly between the semitendinous and semimembranous muscles. In addition to lower limb, particularly the thigh, in humans, shoulder, neck and anterior abdominal wall (between external oblique, internal oblique or transversalis) lipomas are described. These sites have not been reported in dogs. The clinical signs caused by intermuscular lipoma are a result of the space-occupying mass. The lesion usually appears as a slow growing, and non-painful. In this case, the lesion had been presented eleven months prior to the examination at our hospital although in the last four months the mass quickly grew. Radiography, ultrasonography and cytologic examination of fine-needle aspirates established that the mass was fat, but did not suggest that it was intermuscular.