A rare form of calcinosis in patients with systemic sclerosis-myositis overlap: report of four cases.

Objectives: Calcinosis is a well-described entity that occurs in patients with systemic sclerosis (SSc) and dermatomyositis (DM). Calcinosis in SSc typically occurs over pressure points and is usually nodular. We present a case series of four patients with SSc with a much rarer, diffuse form of calcinosis to illustrate this poorly recognized pattern of extensive and debilitating disease.

Methods: Four patients with SSc and extensive calcinosis were identified from patients attending a tertiary rheumatology centre in the preceding 3 years. Their electronic case notes, radiographic images and medical photographs were reviewed.

Results: All four patients had the diffuse cutaneous subtype of SSc (dcSSc) and additionally a myositis overlap. This was in the context of 102 of 461 (22%) patients with SSc whose clinical details had been recorded in the preceding 3 years having dcSSc. Their ages at diagnosis ranged from 27 to 65 years. Three were female, two were anti-Scl70 antibody positive, and two were anti-PMScl antibody positive. Development of calcinosis occurred between 1 and 6 years after onset of SSc. Plain radiography showed very extensive calcinosis in various sites, distributed in a pattern akin to sheets of calcium-containing deposits in the skin and subcutaneous tissue.

Conclusions: Although calcinosis is common in SSc, extensive sheet-like calcinosis is very rare. Our experience suggests that when this form of calcinosis does occur, this is in the context of the diffuse cutaneous subtype of disease and with myositis overlap. The four cases described should raise awareness of this unusual and extensive pattern of disease.