You notice a lump on your cat’s flank, and the vet says she wants to examine it with cytology but may have to proceed to biopsy. What exactly are cytology and biopsy, and what’s involved?
Cytology is an examination of cells under a microscope. They are collected via fine needle aspirate. That means the vet takes a syringe identical to the one used for vaccinations, inserts it into the lump, and pulls on the plunger to draw material from the lump into the needle. A pathologist then makes a diagnosis after looking at the cells under a microscope — or determines whether a biopsy is needed.
A biopsy is the gold standard for making a diagnosis because it preserves the architecture of the tissue rather than just examining some individual cells. It requires excising a piece of the lump. That allows the pathologist to examine cells in relationship to each other.
A biopsy costs two to three times more than an aspirate because it often requires that the cat be under general anesthesia to remove a piece of tissue. But it’s worth it. If a bump or lump does turn out to be cancerous, a biopsy can confirm the type of malignancy (which cytology can often do, but not always). Biopsy can also tell how serious the malignancy is by grading it and thereby allowing the veterinarian to make relevant treatment decisions.