THU0612 Bone sarcoidosis: a retrospective multicenter study of 27 cases

Background Studies on bone involvement of sarcoidosis (BS) are scarse. Objectives To analyse in depth main features, treatments and follow up of patients presenting a BS. Methods Among 926 patients with a proved sarcoidosis from four tertiary hospitals in Paris (France) seen between 2000 and 2015, all cases of BS were retrospectively analysed for demography, clinical features, biological tests and imaging results. Inclusion criteria were a) a bone biopsy with epithelioid granuloma and no casein necrosis, or b) radiological evidence of BS, after exclusion of other diagnoses. Results 27 out 926 (2.9%) sarcoidosis patients fullfilled inclusion criteria for BS. Most patients were caucasian (56%), M/F sex ratio 1.5, 30% were active smokers, mean age at sarcoidosis diagnosis was 39±12 years and at BS diagnosis 43±11 years. Extra-osseous involvement of sarcoidosis was found in lymph nodes (93%), lungs (78%), skin (52%), CNS (33%), ENT (33%), and heart (19%). BS was symptomatic in 15/27 (56%) patients i.e. bone pain (15/15), local inflammation (5/15), bone deformation (3/15), arthritis (4/15), and myalgia (5/15). BS was never the revealing symptom of sarcoidosis. BS was more frequently symptomatic when it was a Perthes-Jüngling osteitis and an appendicular skeletton involvement. On imaging exams, BS lesions were found at the spine skeletton alone (14/27, 52%), appendicular skeletton alone (10/27, 37%) or both (3/27, 11%). BS lesions had an aspect of pseudo-metastasis (59%), micro-cysts (Perthes-Jungling, 37%) or Paget disease (4%). Bone lesion was unique in 22% and 26% of patients had more than 10 lesions. When a bone biopsy was done it always confirmed the diagnosis (n=9); in all other cases extra-osseous biopsies confirmed the diagnosis of sarcoidosis. Nine patients received a treatment for BS, i.e. prednisone (n=8, 0.25–1 mg/kg/day), hydroxychloroquine (n=8), and methotrexate (n=5). Response to treatment was complete (n=3), partial (n=4) or nul (n=2). Of note, 21 out of 27 patients received an immunosuppressant for a severe form of systemic sarcoidosis (n=11) or for a steroid-sparing effect (n=10). A relapse of BS was noted in 13 patients, with a mean number of relapse of 2.1–24 After a mean follow up of 49 months, BS was in complete remission (8/27, 30%), partial remission (16/27, 59%) or remained active (3/27, 11%). Conclusions Bone involvement remains a rare manifestation of sarcoidosis. It was symptomatic in 56% of patients, mainly when Perthes-Jüngling osteitis and appendicular skeletton involvement were present. Extra-osseous involvement of sarcoidosis were always present at the time of BS diagnosis. Treatment remains difficult with frequent relapses. Disclosure of Interest None declared