Lump on Cat? Skin Tag, Cyst & Bump Checker — AI Photo Analysis

Most lumps on cats deserve at least a vet check, but urgent signs include: the lump is growing rapidly (noticeable change within weeks), it feels hard and firmly attached to deeper tissue, it's irregular in shape with uneven borders, it's ulcerated or bleeding, your cat seems painful when you touch it, it appeared at a previous vaccination site (possible injection-site sarcoma), or your cat has other symptoms like weight loss or lethargy. Cats are especially prone to injection-site sarcomas, so any firm lump developing at a vaccination site — even months or years later — should be checked promptly. A fine needle aspirate (FNA) is quick and can determine if it's benign or needs treatment.

A round, ball-like lump under your cat's skin is most commonly a lipoma (fatty tumor), sebaceous cyst, or abscess. Lipomas feel soft, squishy, and move freely when you push them — they're benign fatty deposits common in older or overweight cats. Sebaceous cysts feel smooth and round, like a marble under the skin, and may have a small pore on the surface. Abscesses (from bite wounds or scratches) are more common in outdoor cats, feel warm, may be tender, and can burst on their own. Less commonly, a ball-like lump could be a benign mast cell tumor (more often benign in cats than dogs). A vet visit with a needle aspirate is the only way to know for sure.

Some cat cysts may resolve on their own, but many don't. Sebaceous cysts can persist for months or years, sometimes rupturing and refilling in a cycle. A cat cyst that has burst will drain thick, white or yellowish cheesy material — keep the area clean but don't squeeze it, as this can cause infection. Ceruminous cysts (in the ear canal) and follicular cysts typically don't resolve without treatment. If a cyst is small, not growing, and not bothering your cat, your vet may recommend monitoring. However, surgical removal is recommended if the cyst keeps rupturing, gets infected, is growing, or is in a location that bothers your cat. Removal is usually simple and curative.

Cancerous lumps in cats can be either hard or soft, which is what makes visual or touch diagnosis unreliable. Injection-site sarcomas (fibrosarcomas) are typically very firm and hard, attached to deeper tissue. Squamous cell carcinomas can feel hard and ulcerated. However, some mast cell tumors feel soft, and some lymphomas under the skin can feel squishy. The general warning signs are: firm and fixed (doesn't move), rapid growth, irregular borders, ulceration or bleeding, and location at a previous injection site. Soft, movable lumps are more likely benign (lipomas, cysts), but exceptions exist. Always get any new or changing lump checked by a vet — a needle aspirate is the only reliable way to distinguish benign from cancerous.

Cat skin tags are benign and usually don't need removal unless they're causing problems. If removal is needed (the tag is getting caught, bleeding, or irritating your cat), your vet can remove it by surgical excision, cryotherapy (freezing), or cauterization — all quick procedures, often done under light sedation. Never try to cut, tie off, or remove a skin tag at home — you risk bleeding, infection, and pain, and what you think is a skin tag could actually be a tick (check for legs) or a small tumor. Cat skin tag removal cost typically ranges from $100-$300 depending on location and method. Skin tags on the chin and ear are most common in cats.

Several things can look like a skin tag on a cat: Ticks are the most common mimic — an engorged tick looks remarkably like a skin tag. Look for tiny legs near the base to distinguish them. Warts (papillomas) can look similar but are rougher in texture. Small mast cell tumors can appear as a smooth, raised bump similar to a skin tag. Fibropapillomas are virus-caused growths that can mimic skin tags. Basal cell tumors (usually benign in cats) can start as a small raised bump. If you're unsure whether it's a skin tag or tick, don't pull it — a tick improperly removed can leave its mouthparts embedded. Visit your vet for safe identification and removal.

This is where cats differ significantly from dogs. In dogs, mast cell tumors are often malignant and aggressive. In cats, cutaneous (skin) mast cell tumors are much more likely to be benign — the majority can be cured with simple surgical removal alone. However, there are two types in cats: cutaneous (on the skin, usually benign, good prognosis) and visceral/splenic (internal organs, more serious). Siamese cats are predisposed to developing cutaneous mast cell tumors. The key is proper diagnosis through a fine needle aspirate or biopsy, and complete surgical removal. Most cats with skin mast cell tumors have an excellent prognosis after surgery, with recurrence rates much lower than in dogs.

For cutaneous (skin) mast cell tumors — the type you can see and photograph — most cats live a normal lifespan after surgical removal. Skin mast cell tumors in cats are generally benign, and complete surgical excision is often curative with low recurrence rates. Siamese cats may develop multiple skin mast cell tumors but the prognosis remains good. For visceral (internal) mast cell tumors — particularly splenic — the prognosis is more guarded, with median survival times of several months to a year with treatment. The important thing is: any lump on your cat that could be a mast cell tumor should be checked and removed early. Early surgical removal of skin mast cell tumors in cats almost always leads to an excellent outcome.