Juvenile dermatomyositis (JDM) is a rare disease but it is the most common inflammatory myopathy in children. It is an autoimmune vasculopathy which primarily affects skin and proximal striated muscles. Involvement of major organs like heart, lungs, and gastrointestinal tract may lead to irreversible organ damage and life threatening complications and death. Calcinosis, a dystrophic calcification of unknown cause, is a significant sequelae of JDM in which there is pathological deposition of calcium in skin, subcutaneous tissue, muscle and tendons in patients who has generally normal calcium and phosphorus levels.

It may lead to impaired physical function and impaired quality of life.

Unlike adults with dermatomyositis, calcinosis is more common in JDM as it occurs in up to 70% of cases [1] . Although it may precede JDM diagnosis [2] , its development was related to delayed diagnosis and treatment and chronicity of JDM [3] .

Currently there is no curable treatment for calcinosis but early diagnosis and aggressive treatment of JDM were led to decrease in incidence [4] . Different therapeutic agents have been used to treat myositis-associated calcinosis; however, their therapeutic effects were variable. Rituximab is a biologic agent which showed efficacy in treatment different rheumatological conditions including dermatomyositis [5] [6] . Herein, we report its favorable effect on treatment of calcinosis in 4 children with JDM with severe calcinosis and disability.

A retrospective chart review of 4 children with JDM and severe calcinosis who were diagnosed at King Abdul Aziz University Hospital, Jeddah, Saudi Arabia and received rituximab for relapsing or polycyclic JDM course between March 2008 and July 2014 was conducted. Diagnosis of JDM was based on the criteria proposed by Bohan and Peter [7] .

Diagnosis and follow up of calcinosis was clinically and by radiologically by X-ray by a pediatric rheumatologist and radiologist.

Review data included: age of patients at onset of JDM symptoms and at diagnosis, clinical and laboratory criteria which included: Creatinine Kinase (CK), Lactate dehydrogenase (LDH), Aspartate aminotransferase (AST), Alanine aminotransferase (ALT) levels as well as MRI and muscle biopsy results at diagnosis, complications, disease course and duration of follow up.

Data about calcinosis onset, sites, severity and its progression were also included.

Treatment used for JDM as well as calcinosis management before, during or after Rituximab introduction and outcome of JDM and calcinosis were recorded. Further data about rituximab therapy included: dose, number of courses and adverse effects

Approvals from medical research and ethical committee of King Abdul Aziz University Hospital (KAUH) as well as written informed consents from the patient’s caregivers for publication of these case reports and any accompanying clinical data or images were obtained before writing this report.

4 patients (2 male, 2 female),interval between onset of symptoms and diagnosis was 6 - 12 months, course of JDM was polycyclic or relapsing, duration of follow up was 5 - 7 years.

Calcinosis was present in one patient at diagnosis and at 9, 13 and 16 months after diagnosis.

All patients had calcinosis affecting elbows, hands, thighs, knees, ankles and buttocks.

Calcinosis was severe causing ulceration, recurrent skin infections, joint limitation, severe disability and inability to walk. It was not improving despite improvement in muscle and skin function with different disease-modifying antir- heumatic drugs (DMARDs) and/or bisphosphonates, colchicine and warfarin (Table 1 and Table 2).

Reason to start rituximab was inadequate disease control, disability and frequent relapses.

Only one patient given 2 courses of rituximab; others were given one course.

All patients received steroids and more than one DMARD before starting rituximab and were continued thereafter, follow up after rituximab was 3 to 5 years.

All patients had improvement in disease activity and frequency of admissions especially due to complications of calcinosis. One patient had complete clearance of calcinosis by 2 years, others had significant improvement in calcinosis with no new lesions, decreased sites and density and decreased calcinosis-related contractures. There were no serious side effects to rituximab.

Case 1:

7 years old who was referred to pediatric rheumatology clinic due JDM, after a history of proximal muscle weakness, myalgia and calf muscle tenderness which was associated with typical heliotrope rash and nail fold capillary changes, she was on oral steroids.

Her laboratory work up in pediatric rheumatology clinic showed: Creatinine kinase 2154 U/L, LDH: 230 U/L, AST 190 U/L ALT 217U/L, ANA 1:1280, MRI showed perimuscular edema and increased signal intensity in fat suppression on T2 weighted image.

She had calcinosis at both elbows clinically and X-ray showed further calcium