In school I actually really enjoyed cytology so this case of the day is for future veterinarians - ps I’m not a pathologist so I don’t have the answer!
Signalment is important in the history and case presentation. So this case is a 15-year-old MN DSH who presented with a lump on his chest. The owner notes that it seems to be bothering him. The left side under his armpit is getting bigger with time, but just started noticing a few lumps in the past three days. Still eating, drinking, no vomiting or diarrhea, had a mass removed last year but it was never sent for histopath.
On physical, the cat is morbidly obese, not unusual for a domestic cat. Mild to moderate dental disease, two dermal masses with normal skin, and one larger mass that appears in the subcutaneous fat in the left axilla. All are firm, the largest being about 2 cm, ovoid in shape. Otherwise unremarkable PE.
The first diagnostic step to identifying lumps is a fine needle aspirate. We cannot tell by gross appearance, looking and feeling with our own eyes, we need a cytological sample. I personally use a 25g hypodermic needle for sample collection without a syringe during the ‘aspiration’ with redirection about 20 times, pending blood contamination. I learnt this technique from watching an intern, who is now an oncology resident, when I was in my final year of vet school. I like to take multiple samples, because my goal is to collect a diagnostic sample. I often stain a few slides in hospital and send a few.
The slides were stained in standard diff quick style. These images are taken with my phone through the microscope on 100x oil immersion. I think what I’m looking at are basal epithelial cells.
This is where I make a differential list of possible diagnoses of lumps in a cat. However, I am not a cytology expert. 6 of the 8 slides were sent to the pathologist where they will use their special stains and expertise to tell me what cells these are coming from. Then we can make an informed decision, get some information on prognosis for the cat and his lumps, and see if we need wide excisional margins to remove the lumps. I’ll try to remember to come back and let you know what the pathologist says!