Please help me to diagnose my cat’s lumps

Please help me to diagnose my cat’s lumps

by Julie Kowalski
(Roseville, MI, US)

Spaz Lounging

Spaz Lounging

My cat has reoccurring black lumps that come and go. The first one was very small and we assumed it was a wart or pimple. It eventually disappeared but another would appear in a different spot.

The one he has now is about a quarter in size. This has been going on for a few years and recently he has lost some weight which may be due to his age OR that we switched to a lower fat diet due to our other cats being over weight. Could this be a serious issue?


Hi Julie... thanks for visiting and asking. I am not going to diagnose but simply refer to the best cat health book on the market.

Looking up the index we have one reference to "lumps on or beneath the skin" and two pages.

At page 167 such lumps are described as tumors either benign or malignant (cancerous).

Benign growths grow slowly and do not spread. Cancerous growths can "enlarge rapidly" over weeks and months. They may bleed and ulcerate.

At page 132 the authors provide a list of conditions that cause lumps or bumps on or beneath the skin. I will list them with my comment.

Abscess - not applicable, I feel. These are as a result of bites and puncture wounds. They are not black but red and inflamed.

Cancer - a cancerous lump enlarges rapidly, is hard. A mole that spreads and/or ulcerates might be cancerous. A test needs to be done on the lump to confirm if it is cancerous or not. I don't feel that the lumps you describe are cancerous. See Cat Skin Cancer.

Epidermal inclusion cyst - firm and smooth lump beneath skin. Not applicable it seems.

Grubs/Cuterebra - not applicable as these have a hole in the center for the grub to breath.

Hematoma - clotted blood beneath the skin. Caused by trauma. Blood clots are dark in colour. Could they be blood clots? Does Spaz go out a lot? Might he be getting injured?

Mycetoma - nodule beneath skin. Open "tract to surface" that drains a substance - not applicable on your description.

Skin papilloma - growths from the skin and look like wart or "piece of chewing gum stuck to the skin". These are not painful or dangerous the book says. Are the lumps you describe painful to Spaz? It seems not. This could be the condition.

Sporotrichosis - nodule on skin with hair loss and break in skin - not applicable it seems.

You should have the growth checked out by a vet to find out if it is benign. I sense that it is benign but don't count on that.

Good luck.

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