Background Chronic recurrent multifocal osteomyelitis (CRMO) is a bone inflammatory disorder characterized by osteolytic, usually multiple, symmetric lesions. Diagnosis is one of exclusion, and no standardized therapies are available. Presumed deregulation of the interleukin (IL)‐1β axis, as observed in 2 monogenic autoinflammatory conditions such as Majeed syndrome (LPIN2 mutations) and deficiency of IL‐1 receptor antagonist (IL1RN mutations) with CRMO‐like bone involvement, suggests the blockade of IL‐1 as potentially useful also in this condition, even if scarce data are available. Case presentation We report the case of a 13‐year‐old girl affected by a multidrug‐resistant and pyoderma gangrenosum‐complicated CRMO treated with canakinumab, a human monoclonal antibody targeting IL‐1β. Conclusion In this young patient pyoderma gangrenosum and CRMO showed a rapid and satisfactory response to canakinumab, although over time a decreased efficacy in controlling bone disease was observed.

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.Pyoderma gangrenosum (PG) is a rare neutrophilic dermatosis, characterized by unknown aetiology and sterile neutrophilic infiltrate on histological examination, clinically showing recurrent skin ulcers and mostly affecting lower limbs areas. In 2/3 of the cases, PG is secondary to another disorder such as inflammatory bowel and lymphoproliferative diseases, infections, rheumatic diseases and auto-inflammatory syndromes. The paper describes the cases of three paediatric patients showing the association of PG with rheumatic conditions such as Behçet’s disease, chronic recurrent multifocal osteomyelitis (CRMO) and PAPA (Pyogenic Arthritis, Pyoderma gangrenosum and Acne) syndrome and proposes a diagnostic flow-chart to help paediatricians recognize PG and associated conditions.