Chronic recurrent multifocal osteomyelitis in association with chronic inflammatory bowel disease: entheropathic CRMO

The enterogenic reactive arthritides and entheropathic spondyloarthropathies are well-known entities. The so-called gut iteropathy concept offers an interesting working hypothesis to link the gut inflammation and the lymphocytic infiltration of the synovium. However, the association of rheumatic diseases belonging to the entity of the SAPHO syndrome with inflammatory bowel diseases (IBD) has only been rarely described in the literature. Among 138 cases of our (heterogenic) SAPHO cohort, we detected 5 patients (1 male, 4 females) with a proven association of SAPHO syndrome with IBD (in 4 cases Crohn's disease, in 1 case ulcerative colitis). Two patients belonged to the juvenile-adolescent form and 3 to the adult form of SAPHO syndrome. In all cases the underlying osteoarticluar disease was classified as chronic recurrent multifocal osteomyelitis (CRMO), 2 of them presenting as inflammatory anterior chest wall syndrome. There was a strong association with psoriatic pustular dermatitis. Thus, we present 5 cases of enteropathic CRMO demonstrating several analogies to the enteropathic spondyloarthropathies. Both disease entities have in common i) metachronic development with osteoarticluar manifestations often preceding the gastrointestinal disease; ii) Crohn's like lesions that may develop from the stomach to the colon; iii) concomittent or intermittent skin pustulosis which mostly resolves; iiii) the gastrointestinal disease that often dominates the whole syndrome namely in the longterm follow-up. We suggest to transfer the hypothesis of the gut-synovium axis of enteropathic spondyloarthropathies to the entity of CRMO. This concept offers an opportunity to link the target organs gut mucosa, bone marrow and the skin via homing of antigen specific lymphocytes. This concept may help to better understand the pathogenesis of the Skibo (i.e., skin-bone) disease CRMO.