Faecal Occult Blood Test

Case of the Month (Emma Scurrell January 2011)

A cutaneous infiltrative lipoma in a 6 year old female Labrador Retriever

The following are H&E sections from an incisional biopsy taken from a subcuticular mass of the left flank which clinically appears firmly fixed to the underlying tissue.

Fig 1. An H&E section of the subcuticular mass reveals sheets of well-differentiated neoplastic lipocytes which infiltrate the underlying skeletal muscle.

Fig 2. An H&E section at higher magnification. Note how the neoplastic lipocytes individualise the skeletal muscle fibres. 

Final Diagnosis

Infiltrative lipoma 


These are uncommon neoplasms in the dog and are typically nonencapsulated, infiltrate along fascial planes and invade muscle. Although they do not undergo malignant transformation or possess any metastatic potential, they may require more radical surgical excision due to their infiltrative nature. Females are predisposed and commonly affected sites include the neck, trunk and proximal limbs.

The neoplastic lipocytes of an infiltrative lipoma essentially resemble the lipocytes of normal adipose tissue and confirmation of the diagnosis requires histopathological evaluation for infiltrative behaviour. It is worth noting that obese dogs may have small amounts of fat within underlying skeletal muscle bundles and therefore small incisional or trucut biopsies should be avoided otherwise confirmation of an infiltrative lipoma may not be possible.

Previous Monthly Cases

Hypertensive Retinopathy January 2010
FIP in a cat - uncommon presentation February 2010
Phaeohyphomycosis    March 2010 
Scleral Rupture April 2010
Canine and feline epulides May 2010
Erythema multiforme in a labrador retreiver June 2010
Keloidal fibrosarcoma in a labrador retreiver July 2010
Cutaneous epitheliotropic lymphoma  August 2010 
Benign cutaneous histiocytoma  September 2010 
Iridociliary adenoma October 2010
Proliferative thrombovascular necrosis of the pinnae November 2010
Signet-ring cell carcinoma in the stomach of a dog December 2010

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Faecal Occult Blood Test