Mass on the left hind foot of a cat
A fine needle aspirate was obtained from a mass lesion on the left hind foot of a nine year old male castrated domestic longhair cat. Smears of the aspirate were submitted to the Animal Health Diagnostic Center at Cornell University for examination. The mass was located over the lateral aspect of the metatarsophalangeal joint. The mass was first noted approximately 2.5 months before sampling. At that time, the owner reported a “pea-sized” mass on the lateral aspect of the paw. The mass grew slowly over the next several weeks and measured 2.3 x 1.4 cm at the time of sampling. The mass was described as a rounded, raised, poorly haired to alopecic, soft to slightly firm, movable, non-painful mass with no deep attachments. The patient did not appear to be bothered by the lesion. The mass was non-painful on physical examination and no lameness or altered grooming behavior were reported.
Examine the provided images from the aspirate of the mass, then answer the following questions:
- What general lineage would you assign to these cells?
- What are your differential diagnoses for the mass?
Answers on the next page