A cyst is a small sac in or under the skin. Some cysts in cats are lined with skin-like cells and slowly fill with keratin, the tough protein that skin and hair are made of [1]. Vets often call these epidermoid or keratin cysts.
Do not squeeze a lump on your cat’s skin. If your cat has a new lump, see your vet.
Keratin cysts
Keratin cysts are benign, which means they are not cancer [1]. Inside, a vet usually finds soft or crumbly keratin debris [1].
These cysts are not common in cats [1]. A cat can have just one, or a few in different places.
Why you should not squeeze them
When a hair follicle bursts under the skin, its contents spread into the deeper tissue. That can cause firm swelling, redness, crusts and pain, and it can let an infection go deeper [2]. Pressing on a cyst risks the same thing, so leave it alone and let your vet look at it.
Lumps that look like blackheads
Blackheads in cats are plugged hair follicles (a hair follicle is the small pocket in the skin that a hair grows from). They are the main sign of feline acne, which mostly shows up on the chin and lower lip and can make the chin look dirty [2]. A single, larger blackhead-like lump elsewhere, for example on the head, can be a different kind of growth.
Most of these growths are harmless, but a lump can look much like another kind of lump. Only a vet can tell a cyst from other kinds of lump.
For cysts in dogs, see skin cysts in dogs.
Treatment
Your vet will advise on what to do about a cyst. A lump that is removed can be sent to a lab, which is how a vet confirms what it is [1].
At home, as directed by a vet:
- do not squeeze a cyst or lump [2];
- do not give your cat human or leftover medicines unless your vet says so;
- go back for any recheck your vet books.
When to see your vet
See your vet if your cat has:
- a new lump in or under the skin;
- one lump or several lumps in the skin;
- a growth on the head that looks like a large blackhead;
- a hard, horn-like spike on the skin;
- a lump that becomes red, swollen or sore [2];
- any lump you are unsure about.
The bottom line
Keratin cysts are benign sacs of keratin in a cat’s skin, and they are not common [1]. Squeezing a cyst or a plugged follicle can push its contents into the deeper skin and cause painful swelling [2], so leave it to your vet. Only a vet can tell a cyst from other kinds of lump.
This article is for general information only and does not replace advice from your veterinarian. If your cat has a lump, see your vet.
Sources
- Choi H, Kim KA, Lee DE, et al. Epidermoid Cyst of the Soft Palate in a Geriatric Cat: A Case Report. Veterinary Sciences (MDPI), 2026. CC BY 4.0. https://pmc.ncbi.nlm.nih.gov/articles/PMC13709755/
- Torres SMF. Feline Acne. In: Small and Large Animal Dermatology Handbook, Vol. 2, ch. 3.9. University of Minnesota, 2025. CC BY 4.0. https://open.lib.umn.edu/animaldermatology2/chapter/idiopathic-keratinization-disorders-feline-acne/