What is chronic recurrent multifocal osteitis (CRMO) and how does it relate to SAPHO?
CRMO is a chronic, sterile, inflammatory, and multifocal disease of bone that preferentially affects children. Bone sites involved differ according to the patient’s age. The metaphysis of the long bones is preferentially affected in children and adolescents (which is different than common sites of involvement in SAPHO syndrome), whereas anterior thoracic, vertebral, and/or unilateral sacroiliac lesions predominate in adults (similar to SAPHO). Bone biopsies are necessary to rule out bacterial osteomyelitis, tumor, and eosinophilic granuloma. Adult patients with suspected CRMO should be closely assessed for underlying Crohn’s disease, psoriasis, or another spondyloarthritis. In addition, clinicians should monitor for the development of characteristic skin lesions that would otherwise classify the patient as having SAPHO syndrome. Treatments used have been similar to those used in SAPHO.