Clinical characteristics of scleroderma patients with calcinosis in a single-center cohort

Background/Purpose: Calcinosis is soft tissue deposition of calcium hydroxyapatite crystals in scleroderma spectrum disorder (SSc) patients. In our cohort, ≤5% of SSc patients have confirmed calcinosis. Common in pressure areas, deposits vary in size and shape, are solid or semi-solid, and range from asymptomatic to widespread and painfully disabling. Risk factors, pathophysiology, and clinical outcomes in SSc-calcinosis patients (SSc-Ca) are unknown, and there is no cure.  Therefore, identifying those at risk may lead to understanding of calcinosis development and better management. Herein, we compare clinical characteristics of 17 SSc-Ca patients to 10 control SSc patients without calcinosis.

Methods: Outpatient SSc subjects were invited to enroll as they were seen consecutively in the UMDNJ Scleroderma Program. Clinical information was obtained and calcinosis confirmed by the examining physician or imaging. Fisher’s Exact Test was used to measure significance.

Results: Table 1 summarizes clinical characteristics per group.  SSc-Ca patients were generally older Caucasian females with limited SSc of longer disease duration, with more bowel (OR 5.71, p = 0.107) and fewer pulmonary complications (OR 0.14, p = 0.046). Calcinosis often presented years after SSc onset (mean 16 y, range 1-41 y). About 1/3 of each group also had polyarthritis or myositis.

In this cohort, the most common calcinosis sites were fingertips (100%), IP joints (52%), and elbows (35%). Most subjects (80%) did not consider themselves disabled unless deposits were painful or affected function. Extensive extremity and trunk calcinosis completely disabled 2 patients. Over 50% took analgesics or sought surgical removal as the most common therapy. SSc-Ca patients were more likely to have osteoporosis (OR 12.86, p = 0.018); we observed 2 subjects whose bone density deteriorated rapidly as their disabling calcinosis became widespread.

Laboratory studies showed normal electrolyte and PTH levels in both groups. All subjects were taking vitamin D supplements. The most common antibody was anti-centromere in 44% of SSc-Ca patients and Scl70 in 67% of control patients.

Conclusion: Older Caucasian female subjects with limited SSc more commonly developed calcinosis years after SSc onset, usually involving the hands/fingers. SSc-Ca subjects tended to have osteoporosis, as well as more SSc-related small bowel, but fewer pulmonary complications. It is unclear why some SSc patients develop calcinosis. More studies are needed to evaluate risk factors and clinical outcomes in SSc-Ca patients.

Table 1: Clinical characteristics of SSc subjects with and without calcinosis