Calcinosis Circumscripta and Calcinosis Cutis

What are calcinosis circumscripta and calcinosis cutis?

These two conditions occur when calcium is deposited within the skin. They are usually of minor significance in young dogs and cats but can indicate serious underlying diseases in older pets. These conditions are uncommon in dogs and rare in cats.

Calcinosis circumscripta is the buildup of calcium in a specific area, usually at bony prominences (areas where there is little tissue between the bone and skin) or in the footpads and mouth.

Calcinosis cutis occurs in areas where the skin has been damaged. It has four forms:

• Dystrophic: Calcium levels in the blood are normal, but calcium salts are deposited in damaged tissues.
• Metastatic: Calcium levels in the blood are elevated, and calcium is deposited in areas of damaged tissue. Calcium deposits may occur in multiple areas.
• Iatrogenic: Caused by an external source, such as calcium injections used to treat other conditions.
• Idiopathic: The cause is unknown.

What causes these conditions?

The cause of calcinosis circumscripta is unknown, but inherited factors may play a role. It typically affects large-breed dogs, especially German Shepherds, and often appears in young dogs under two years of age.

The cause of calcinosis cutis varies by type.

• Dystrophic calcinosis cutis typically occurs because of an injury or a reaction to injections or other foreign materials that enter the tissues.
• Metastatic calcinosis cutis in dogs is usually caused by the overproduction of corticosteroids, a type of hormone produced by the adrenal glands. This can occur because of overgrowth of the adrenal glands, cancer of the adrenal glands, or cancer of the pituitary gland, which controls the adrenal glands. A less common cause of metastatic calcinosis cutis in dogs is long-term corticosteroid treatment (e.g., for allergies).
• Metastatic calcinosis cutis in cats is most commonly caused by kidney disease.
• Rarer causes of metastatic calcinosis cutis include diabetes mellitus, lung disease, and malignant tumors that produce abnormal hormones that raise blood calcium levels. These tumors include cancer of the anal glands and cancer of the lymphoid system).

Puppies may occasionally develop calcium deposits during serious illness, but these deposits are temporary and tend to disappear on their own as the puppies get better.

What are the clinical signs of these conditions?

Pets with calcinosis circumscripta usually have one or a few affected areas (lesions) over a bony prominence or in the mouth, particularly the tongue. 

Pets with calcinosis cutis typically have small bumps or raised patches (papules or plaques) with a rough, gritty surface, which may be quite itchy. These lesions may be anywhere on the body but are typically in the groin area, armpits, and along the back. Both types of lesions often develop open sores and discharge chalky material or pus.

Pets with calcinosis cutis caused by the overproduction of corticosteroids may also have muscle loss and a swollen abdomen due to weakened abdominal muscles. Hair loss and blackheads (comedones) may also be present. If the underlying disease is cancer or kidney disease, there may be other signs associated with those conditions.

How are these conditions diagnosed?

• Physical examination: The appearance of the lesions may lead your veterinarian to suspect calcium deposits, particularly when your pet’s age, breed, and clinical history are considered.
• Blood tests: Blood tests can help identify underlying diseases (e.g., hyperadrenocorticism, kidney disease) that cause these conditions. They may also show increased calcium levels in the blood.
• Skin biopsy: A biopsy is needed to confirm the diagnosis. A biopsy is the surgical removal of one or more pieces of a lesion. A veterinary pathologist then examines the tissue under a microscope (a process called histopathology).

How are these conditions treated?

Surgery is the preferred treatment for single lesions of calcinosis circumscripta. While small deposits may slowly be reabsorbed by the body without treatment, larger deposits may be pushed out through the skin. This can cause unpleasant discharge, and the area may not heal properly. Surgical removal is usually preferable in these cases.

Treatment for calcinosis cutis focuses on the underlying cause. In most pets, the lesions slowly clear up once the underlying disease is controlled. A thin layer of dimethyl sulfoxide (DMSO) can be applied to the skin to help break down the calcium deposits while preventing further crystallization. However, little information is available on this treatment in cats.

What is the long-term outlook for these conditions?

With calcinosis circumscripta, single lesions due to causes such as injury can be cured with surgery. Calcinosis circumscripta does not tend to come back after surgery. Calcinosis cutis may get worse before it gets better, as the calcium deposits push out through the skin. The long-term outlook usually depends on the underlying cause.

Should I provide any special care for my pet?

Prevent your pet from rubbing, scratching, licking, or biting the affected areas to reduce itching, inflammation, open sores, infection, and bleeding. Any ulcerated area needs to be kept clean. After surgery, keep the area clean, and do not allow your pet to interfere with the site. Report any missing stitches or significant swelling or bleeding to your veterinarian. If you need additional advice on care after surgery, ask your veterinarian.