Bone Abstracts

Background: Primary tumoral calcinosis is an orphan disease. The data about the incidence of this disease, as well as clinical recommendations for treatment are not presented in the literature.

Presenting problem: Two patients – 11.5 years old boy and 8 years old girl with primary tumoral calcinosis had multiple foci of the subcutaneous calcification, walking impossibility, wheel-chair condition, fatigue, high fever and equinus deformity of the left foot. The patient did not have changes in the calcium-phosphorus homeostasis. The boy had increased C-reactive protein (CRP), more than 200 mg/l (normal value <5 mg\l) and the girl had normal CRP under the corticosteroids. Both patients initially were evaluated as juvenile dermatomyositis and he has been received steroids with methotrexate during years without improvement. The efforts to decrease the steroids provoked fever and elevation of CRP in both. Immunological studies ruled out inflammatory myopathies and other rheumatic conditions. Genetic studies for GALNT3, FGF23 and Klotho genes were done but did not find any specific mutations. The whole-exome sequence was also done but did not find mutations. The morphology assay was identified as typical changes for tumoral calcinosis.

Clinical management: After verification of the diagnosis, the therapy with an interleukin-1β inhibitor – canakinumab: 4 mg/kg every 4 weeks for boy and every 8 weeks for the girl was prescribed. During the treatment in children, the corticosteroids were discontinued without flares, a significant improvement in the patient’s general condition was observed, a decrease in the number of calcinates, and a reduction in inflammation. All children could walk without any support. The boy had a surgery due to deformity of the left foot which was caused by calcification of the Achilles tendon and gastrocnemius muscle without exacerbation.

Discussion: The use of an inhibitor of interleukin-1β as a permanent therapy of primary tumoral calcification allowed to control calcification and improve walking and general condition. This work supported by the Russian Foundation for Basic Research (grant no. 18-515-57001).

Disclosure: The authors declared no competing interests.