I’ve Got You Under My Skin.... Calcinosis and Dermatomyositis

Calcinosis is a challenging aspect in the management of dermatomyositis (DM). Not much is known about this clinical manifestation, which can have disabling results. Dr. L Chung from Stanford University presented an excellent talk called "Calcinosis Associated with Dermatomyositis and Other Connective Tissue Diseases."

Calcinosis is characterized by calcium deposits under the skin. It can present as subcutaneous nodules of various shapes and sizes. In the case of DM, calcific deposits can be plate- or plaque-like and extend over large surface areas. Common locations for calcinosis in DM, in descending order, are on the extremities, trunk, hands/feet, and face. Depending on the location of the calcium deposits, several complications can occur including pain, infections, and compression of nerves and other structures.

The deposits are composed of calcium hydroxyapatite crystals. Interestingly, unlike calcinosis seen in other disorders (e.g., malignancy), in DM the levels of calcium and phosphate in the blood are normal.

Up to 20% of adult and 70% of juvenile DM patients develop calcinosis. The Stanford group analyzed a cohort of 126 adult DM patients to look for clinical features associated with calcinosis. Longer disease duration and presence of fingertip ulcerations were strongly associated with the presence of calcinosis. Certain myositis-specific antibodies were more highly associated with calcinosis; for example, NXP-2 and MDA-5. It was noted that ulceration is an early finding in MDA-5 DM and that calcinosis appears as ulcers heal, at the location of prior ulcerations.

Why does calcification occur? Several different factors are believed to come into play in the pathophysiology of calcinosis, including tissue hypoxia, chronic inflammation, and abnormalities in bone matrix proteins. In fact, osteoporosis has been shown to correlate with vascular calcification in endocrine studies, and bisphosphonates have been shown to improve this calcification.

Knowing this pathophysiology, novel treatment approaches may be developed that target the different steps involved in the pathogenesis of calcinosis. Thus far, treatment options include local steroid injections, laser therapies, extracorporeal shock wave lithotripsy, and surgery. Oral drug therapy includes bisphosphonates, calcium channel blockers, and warfarin, among others. Future therapies may target tissue hypoxia; for example, the use of vasodilators such as PDE-5 inhibitors may be helpful. Therapy targeting inflammation (e.g., TNF inhibitors) may also be a possibility. Finally, regulators of bone metabolosim, such as conventional bisphosphonates and others, like denosumab or teriparatide, might be promising.

Interestingly, despite possible concerns with infection or recurrence, surgery may be one of the most helpful option for areas of calcinosis that are amenable to such interventions. However, the success of surgery may depend on the familiarity of surgeons with calcinosis and is very centre-dependent. Dr. Chung emphasized that in her experience, there is a very low rate of recurrence of calcinosis in locations of previously excised calcium deposits, with the highest percentage of reoccurrence reported at 25%, with rates typically as low as 5-10%.

More reports from ACR 2015