What are calcinosis circumscripta and calcinosis cutis?
These two conditions are the result of calcium being 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 deposition of calcium, usually at bony prominences (i.e., where bone and skin are thinly separated) or in the footpads and mouth.
Calcinosis cutis occurs in susceptible pets in areas where local skin damage has occurred. Calcinosis cutis has two forms:
Dystrophic – occurs when calcium levels in the blood are normal, but calcium salts are deposited in damaged tissues.
Metastatic – occurs when calcium levels in the blood are elevated and calcium is deposited in locally damaged tissues. Calcium deposits may occur in multiple areas.
What causes these conditions?
The cause of calcinosis circumscripta is unknown, but there seems to be a genetic or hereditary component. It typically affects large breed dogs, especially German Shepherds, and often appears in young dogs (under two years of age).
Dystrophic calcinosis cutis typically occurs because of bodily injury or reactions to injections and other foreign materials to which tissues may be exposed.
"In dogs, the most common cause of metastatic calcinosis cutis is the overproduction of corticosteroids, a type of hormone produced by the adrenal glands."
In dogs, the most common cause of metastatic calcinosis cutis is the overproduction of corticosteroids, a type of hormone produced by the adrenal glands. Hyperadrenocorticism (a condition of excessive corticosteroids) can occur because of overgrowth of the adrenal glands, cancer of the adrenal glands, and cancer of the pituitary gland. This gland controls the adrenal glands. A less common cause of metastatic calcinosis cutis in dogs is corticosteroid treatment for extended periods of time (e.g., for allergies). Some dogs are more susceptible to the effects of steroids than others.
Other rarer causes of metastatic calcinosis cutis include kidney disease (the most common cause in cats), diabetes mellitus, lung disease, and malignant tumors that produce abnormal hormones that increase blood calcium concentrations (including 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 spontaneously as the puppies get better.
What are the clinical signs of these conditions?
Pets with calcinosis circumscripta usually have a single lesion over a bony prominence or in the mouth, particularly the tongue.
Pets with calcinosis cutis typically have lesions (papules or plaques) with a gritty rough surface which may be quite itchy. The lesions may be anywhere on the body but are typically in the groin area, under the arms (armpits), and along the back. Pets with calcinosis cutis caused by the overproduction of adrenal gland hormones (corticosteroids) may also have a loss of body muscle and swelling of the abdomen (due to laxity of the muscles). Hair loss and comedones (blackheads) may also be evident. If the primary disease is cancer or kidney disease, there may be other signs associated with these conditions.
Both types of lesions often ulcerate and discharge chalky material or pus.
"Both types of lesions often ulcerate and discharge chalky material or pus."
How are these conditions diagnosed?
Although blood tests and skin biopsy usually diagnose these conditions, the appearance of the lesions often leads your veterinarian to suspect calcium deposits, particularly when the age, breed, and clinical history are considered.
Blood tests can help identify underlying diseases (e.g., hyperadrenocorticism, kidney disease) that cause these conditions, and the tests may show increases in serum calcium. As helpful as blood work is to understand the situation, these conditions are definitively diagnosed by skin biopsy. A biopsy is the surgical removal of one or more pieces of the lesion(s). A veterinary pathologist then examines the pieces of affected tissue under the microscope. This is called histopathology.
How do calcinosis cutis and calcinosis circumscripta typically progress?
In the case of calcinosis circumscripta, single lesions due to causes such as trauma can be cured surgically. Recurrence of calcinosis circumscripta after surgery does not tend to occur.
Calcinosis cutis may get worse before it gets better as the calcium deposits push out through the skin. The prognosis usually depends on the resolution of the underlying cause.
What types of treatment are available?
Surgery is the treatment of choice for solitary lesions of calcinosis circumscripta. While small deposits may slowly resorb without treatment, larger deposits may be pushed out through the skin. This is unpleasant due to the resulting discharge. As well, the area may not heal properly. Surgical removal is usually preferable in these cases.
Treatment for pets with calcinosis cutis focuses on the underlying cause. In most pets, the lesions slowly resolve once the underlying disease is controlled. Topical therapy using a thin layer of dimethyl sulfoxide (DMSO) can be applied to help break down the calcium deposits while preventing further crystallization. However, little information is available on this treatment in cats.
Is there any special care that I should provide to my pet?
Preventing your pet from rubbing, scratching, licking, or biting the problem areas will reduce itching, inflammation, ulceration, infection, and bleeding. Any ulcerated area needs to be kept clean.
After surgery, the area needs to be kept clean, and your pet should not be allowed to interfere with the site. Report any loss of sutures or significant swelling or bleeding to your veterinarian. If you require additional advice on post-surgical care, please ask your veterinarian.