This month is the second in a series of cases involving cancer. It involves an older cat who developed a lump on his head.

LIKE I NEED A HOLE IN MY HEAD...

HISTORY

Frisky was an older cat (14 or 15) who had been generally healthy over the years, but whose owners one day noticed a small lump above his eye. At first it looked like what you'd see with a bug bite (Frisky liked to play with spiders), but after several days had not gone away. In fact, it seemed to be getting bigger.

PHYSICAL FINDINGS

Frisky's exam revealed a soft lump in the skin just above his eyelid. The lump was not painful, but was firmly attached to the bone beneath.

TEST RESULTS

Last month we discussed the value of a needle aspirate. Some tumors that are very firm may not give us useful results, and some tumors have few cancer cells mixed in with normal cells and can be hard to diagnose with an aspirate. But in Frisky's case an aspirate was helpful.

This looks bad. Cancer is often defined as an uncontrolled growth of a group of cells. On this slide we see several cells growing out of control. And, everywhere we looked (the picture here is one of about 20 we could have taken from just one needle aspirate) we saw similar cells. Here's a little more information:

First of all, most normal cells have a single nucleus (the darker purple), which is where the cell's DNA is stored. In most cases, cells reproduce by dividing into two smaller cells which then grow to go on and divide themselves. This process is called mitosis, and some cancers are graded for malignancy based on the number of mitotic figures, or cells in the process of dividing, that are present. Frisky has many mitotic figures. In general, the more mitotic figures, the more malignant the cancer.

Here's a cell with more than one nucleus. I count at least 6 (there may be a couple small, abnormal ones). This cell has gone through several attempts to divide without separating into new cells.

Finally, something we don't see very often, a cell just finishing the process of dividing. If you look closely you'll see that each nucleus is rough where the two would have separated from each other - they probably haven't finished forming yet.

DISCUSSION

Unfortunately, an interesting aspirate meant bad things for Frisky. If we had sent this sample to the lab, it may have been identified as a type of carcinoma. Because of concerns that the tumor had already invaded his skull, Frisky's owners decided against any treatment, and he was euthanized a short time later when the tumor became uncomfortable.

A diagnosis of cancer in a pet often causes many difficult choices for that pet's family. Treatment can involve surgery, chemotherapy, radiation therapy, or a combination of these. Some of these treatments are not available locally and would require travelling as far as Boston. And, when treated, some cancers respond well, some do not. Some can be cured, some cannot. Cancer can be one of the worst things we as pet owners and veterinarians have to face.

In spite of all the bad news, we do have pets who do very well after being treated for cancer. We'll have one of these next month.

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