Calcinosis Cutis (Calcium Stones in the Skin) Causes, Types, Treatment

What is calcinosis cutis?

Calcinosis refers to a buildup of calcium deposits in the soft tissues of the body. Calcinosis cutis refers to deposits of calcium salts in the skin tissue. Calcium deposits in calcinosis cutis may also extend beyond the skin, and affect the subcutaneous tissue, muscle tissue and organs lying beneath the skin. Calcinosis cutis can be a painful condition that may lead to the formation of ulcers.

The skin may become severely disfigured. Gangrene formation may also occur in some rare cases. Calcinosis cutis is a rare condition. Men and women of all ethnicities can get affected by this condition. However, individuals at different life stages may be susceptible to different types of calcinosis cutis. Moreover, certain ethnic groups seem to have a relatively higher incidence of calcinosis cutis.

Signs and Symptoms

In the initial stages of calcinosis cutis, signs and symptoms are typically absent. As the calcium deposits begin to grow, the following signs and symptoms may become evident:

  • The area around the calcium deposits may become tender and painful.
  • Skin lesions or ulcers may appear at the sites of calcium deposits.
  • Calcium deposits in the skin may assume the form of nodules, patches, or pimples that are yellow or white in color.
  • A cream-colored discharge may occur from the skin lesions that appear at the sites of calcium deposit.
  • Calcium deposits around joints may reduce the movements at the joints and cause stiffness.
  • In rare cases, gangrene may develop in the affected skin area.

How is Calcium Deposited in the Skin?

Calcium is a critical element of many physiological processes in the human body. The majority of the calcium deposits in the body occur in the skeletal system. Small amounts of calcium are also stored within the cells of the body. Calcium is also present within the blood and other body fluids. The amount of calcium in the cells and body fluids is regulated through homeostatic mechanisms.

An abnormal increase in the amount of calcium in tissues of the body can lead to metabolic disturbances. Excess calcium starts to deposit in the soft tissues of the body. Most of the calcium deposits contain calcium phosphate. In calcinosis cutis, deposits of calcium salts predominantly occur in the dermal layer of the skin. However, the deposits can also extend into the subcutaneous tissues.

Deposits of calcium salts in soft tissues may occur when the levels of calcium and phosphate ions in the bloodstream increase beyond their normal physiological levels. Excess calcium may precipitate out of the body fluids. However, the exact mechanisms are unclear.

Calcium deposits may occur even when the level of calcium in the blood and body fluids is normal. For example, certain proteins may bind phosphates in the blood during a response to tissue injury. The bound phosphate may then attract calcium, leading to the formation of calcium deposits.

Types of Calcinosis Cutis

Depending on the cause of calcium deposition, calcinosis cutis can be classified into different types. Calcinosis cutis caused by different conditions are characterized by different locations of calcium deposits. For example, calcium deposits in dystrophic calcinosis cutis occur predominantly at the sites of tissue injury.

Calcium deposits in iatrogenic calcinosis cutis occur mainly at sites where medical procedures have been conducted or drugs have been administered. Calcium deposits in metastatic calcinosis cutis are commonly seen around the knee and shoulder joints.

Dystrophic calcinosis cutis

Dystrophic calcinosis cutis results from calcium deposition that is triggered by tissue injury. This is the most common type of calcinosis cutis. Different types of tissue damage (such as inflammation, necrosis, and malignancy) can result in dystrophic calcinosis cutis.

Metastatic calcinosis cutis

Metastatic calcinosis cutis is mainly associated with an underlying malignancy. Abnormally high levels of calcium (technically referred to as hypercalcemia) and phosphorus (technically referred to as hyperphosphatemia) in the blood are found to occur in this condition.

Iatrogenic calcinosis cutis

Iatrogenic calcinosis cutis occurs in response to certain medications or treatments. Discontinuation of the causative medications or treatments can lead to a reversal of the condition.

Idiopathic calcinosis cutis

Idiopathic calcinosis cutis occurs due to unknown reasons. Tissue damage or elevation of calcium and phosphate levels in the blood are not associated with idiopathic calcinosis cutis. The condition is also not found to be associated with any iatrogenic causes.

Causes of Calcinosis Cutis

The following are some of the underlying conditions that have been associated with different types of calcinosis cutis:
Dystrophic calcinosis cutis has been associated with a variety of conditions such as acne, skin infections, diseases of connective tissue, varicose veins, tumors, trauma, and inflammation of subcutaneous fat.

Metastatic calcinosis cutis is associated with malignancies. Other conditions that are associated with metastatic calcinosis include renal failure, hyperparathyroidism, calciphylaxis, sarcoidosis, milk-alkali syndrome, excessive amounts of vitamin D and paraneoplastic syndrome.

Iatrogenic calcinosis cutis is associated with medical treatments like injections of phosphate and calcium, prolonged use of electrode paste consisting of calcium, and repeated heel stick blood sampling in newborns.

No conditions have been associated with idiopathic calcinosis cutis. Even though many conditions have been associated with the occurrence of calcinosis cutis, the current theories about the exact causes are incomplete. This is because calcinosis cutis does not occur in every individual who has the predisposing conditions mentioned above. There may also be a genetic contribution to the development of calcinosis cutis since the condition has a relatively higher incidence in certain populations (such as South Africans).

Diagnosis of Calcinosis Cutis

Initial diagnosis of calcinosis cutis can be made based on the appearance of lesions on the skin. The presence of underlying hypercalcemia strengthens this diagnostic conclusion. Calcium deposits in calcinosis cutis are radio-opaque and may get detected during CT scans or X-ray examinations. Microscopic examination of biopsy samples from the lesions can help in a definitive diagnosis of calcinosis cutis.

Treatment of Calcinosis Cutis

Since the exact cause of calcinosis cutis is not understood, there is no definite cure for calcinosis cutis. However, certain medications may help in controlling inflammation and reducing calcium deposits. Examples of such medications include antacids, calcium mimetics, calcium-channel blockers, and diphosphonates. These agents disrupt normal calcium and phosphate metabolism. In severe cases, surgical removal of calcium deposits may be resorted to. However, it is important to note that calcium deposits tend to recur after their surgical removal. Therefore, surgery is not a cure for calcinosis cutis.

Images sourced from Dermatology Atlas.

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