Granulomatous Dermatoses in Cats

Skin bumps can be related to a great number of underlying conditions, some harmless and some potentially life threatening. Veterinary assessment is required to determine the exact type of granulomatous dermatoses present in the cat. Skin bumps may irritate the cat and cause it to scratch open wounds in the skin, leaving the cat vulnerable to bacterial infection. The term “dermatoses” excludes conditions of the skin that arise from improper immune inflammatory cell reactions. These inflammations are referred to as “eosinophils granulomatous”, and often manifest as allergies.

Any bumps on the skin of a cat may be referred to as granulomatous dermatoses. This condition is also sometimes called “sterile nodular dermatoses”. Skin bumps are often solid tissue masses that are raised from the skin and usually reach diameters greater than 1cm. These bumps may form due to substances or reactions in or outside the body. Bumps may form anywhere on the skin surface or around the mouth cavity.

Bumps on the skin of a cat may vary in shape, size, and number. The bumps may also change or move over time. It is not uncommon for bumps to disappear between flare-ups. Symptoms are as follows:

• Raised bumps
• Erosions
• Crusts or scabs
• Alopecia (hair loss)
• Scaling of the skin
• Lesions
• Lip ulcers
• Oozing
• Discoloration
• Large tumors
• Excessive grooming

Skin bumps may develop in relation to a large number of underlying problems within the cat. Identifying the cause in your cat will greatly assist in the treatment of granulomatous dermatoses. Common possible causes include:

• Spherocytosis (red blood cell disease)
• Nodular dermatofibrosis (bumps composed of elastic skin relating to kidney disease)
• Diabetes mellitus
• Hyperlipoproteinemia (inability to break down fats)
• Amyloidosis (protein deposits)
• Viral infections
• Insect bites
• Cutaneous histiocytosis (lymph node disorder)
• Cutaneous xanthoma (fat deposits)
• Calcinosis cutis (calcium deposits)
• Skin stones
• Cancer
• Foreign bodies in the skin

Once at a veterinary clinic or animal hospital, your cat will undergo a complete physical examination. You will need to provide the vet with the cat’s medical history. The skin bumps themselves will require visual assessment and a dermatological examination will be performed. Affected skin tissue will be removed in a biopsy. Samples will be sent for a microscopic histopathological examination to fully diagnose the issue.

Skin scrapings may also be needed to test and identify possible causes of infection, including bacteria, mycobacteria (an especially harmful germ) and fungi. Allergy testing involving food trials and flea bite trials may be needed to differentiate granulomatous dermatoses from allergy symptoms. The cat will need to be checked for the invasion of parasites internally or throughout the skin.

The appropriate course of treatment depends on the underlying cause of the skin bumps. Some conditions are relatively harmless and require no treatment, while others may merit the need for hospitalization of the cat. Certain underlying conditions are not curable and may eventually become fatal, as is the case with most malignant histiocytosis and severe amyloidosis.

Surgical Removal 

Many conditions can be treated with surgical removal of skin bumps. This is especially the case if only a small number of bumps exist in one localized area. Conditions that may be treated this way include minor amyloidosis, spherocytosis, calcinosis circumscripta, and sterile panniculitis. General anesthesia is required for surgery and extensive at-home care may be needed.

Topical Therapy 

Medicated shampoos and washes may be used to soothe skin and clean out any lesions on the cat.

Steroids and Medication 

Certain underlying conditions may be treated with prescriptions of steroids or medications. This can include the injection of steroids on a regular basis for a period of time. These treatments can help to manage conditions like diabetes mellitus and  hyperlipoproteinemia.

Antibiotics 

If infection is present, or of surgery has been performed, antibiotics will be prescribed for a time to clear the body of harmful bacteria. 

Antifungal Medication

If fungi has been identified in the cat, appropriate antifungal medication will be prescribed.

Post surgical care, including daily monitoring of the incision site, will be needed to check for signs of infection. The cat must be prevented from interfering with the wound. Activity during this healing period should be limited. If the cat is receiving steroid or medication treatment, blood work and urinalysis may be needed every six months to ensure organ damage is not being caused. If dimethyl sulfoxide has been prescribed, the frequency of blood work may be increased to once every two weeks to check calcium levels. 

It is difficult to predict if granulomatous dermatoses will recur due to the various causes of the condition. It may be beneficial to keep your cat indoors to limit exposure to infectious agents. Regular blood testing at an annual vet visit may also help in identifying conditions before skin symptoms develop, as early diagnosis can lead to a better prognosis.