July 20, 2017
A 10-year-old boy with several months of intermittent and progressively worsening lower back pain
Chronic Recurrent Multifocal Osteomyelitis (CRMO)
- Background:
- Autoinflammatory disorder of bone primarily in children and adolescents
- Association with the adult disease equivalent SAPHO (synovitis, acne, pustulosis, hyperostosis, osteitis) further suggests autoinflammatory etiology
- Clinical Presentation:
- Characterized by fever, multifocal nonpyogenic inflammatory osseous lesions, and a relapsing and remitting course
- Typically involves the metaphysis or metaphyseal equivalents; most common sites include the lower extremities, medial clavicle, spine, and pelvis
- Key Diagnostic Features:
- Prolonged and intermittent clinical course; presents in unusual locations compared with infectious osteomyelitis; bilateral symmetry; multifocality; lack of abscess formation, fistulas, or sequestra; lack of response to antibiotics; comorbid inflammatory disorders
- Negative bone biopsy and cultures with inflammatory cells; mildly elevated ESR and CRP
- Mutations in either pyrin or tumor necrosis factor receptor family
- A diagnosis of exclusion, with actual prevalence likely higher than reported in the literature
- Differential Diagnoses:
- Infectious osteomyelitis: bone destruction with soft tissue component and positive biopsy and cultures
- Langerhans cell histiocytosis: vertebra plana, destructive osseous lytic lesions ± pathologic fracture, paraspinal/epidural mass, spinal canal extension; typically single-level spine involvement
- Ewing sarcoma and other malignancies (eg, leukemia, lymphoma): aggressive permeative osseous destruction
- Hypophosphatasia: rickets-like skeletal changes, fractures (infantile type)
- Juvenile idiopathic arthritis: spinal subluxations, fusions, and growth disturbances
- Treatment:
- There is a proven lack of response to long term antibiotics; disease course is unpredictable, and a relapsing/remitting course may occur.
- NSAID and steroids are used for symptom relief. Biologics including infliximab, as well as bisphosphonates, have both demonstrated clinical improvement and are considered to be the most helpful treatment agents by patients.
- Early referral to a pediatric rheumatologist and a low threshold for requesting MR imaging (including whole-body MR imaging to screen for multifocal lesions that may be clinically asymptomatic) can help to reduce the diagnostic delay.
