Case Presentation: Case 1: A 3-year-old female with no significant past medical history presented with a 5-week history of recurrent fevers as well as bilateral lower extremity pain with difficulty to ambulate. Imaging of the femur revealed focal lucencies in the proximal femoral shaft. The leading diagnosis at admission was malignancy given the length of fever, the imaging, and the lack of inflammatory markers expected in infection. Bone marrow biopsy was negative for any neoplastic process. CT of the chest and abdomen was negative. Two bone biopsies demonstrated only non-specific chronic inflammation compatible with chronic recurrent multifocal osteomyelitis (CRMO). She was started on steroids, methotrexate, and Adalimumab. Case 2: A 12 y.o. female with a history of ulcerative colitis (UC) presented with several weeks of worsening joint pain and fever. Her pain started in her lower back. At admission, she also complained of pain in her left shoulder, right knee, and her great toes. She had raised inflammatory markers. X-rays of the R knee and lumbar spine were unremarkable. Bone scan showed increased uptake in the left acromion. An MRI was obtained and showed enhancement of the left acromion with an overlying small collection consistent with osteomyelitis. She underwent I&D of the left shoulder with cultures and a bone biopsy. There were copious amounts of pus in the left shoulder and bilateral great toes. She was empirically started on vancomycin and ceftriaxone. She continued to spike fevers on the antibiotics. The OR cultures remained negative and antibiotics were discontinued. Bone pathology resulted in osteomyelitis with areas of necrosis and granulomatous inflammation consistent with CRMO. She was started on steroids and methotrexate.
Discussion: The first case highlights that CRMO can begin as a unifocal lesion. Imaging findings are characteristic but can mimic other pathologies. The second case highlights the association of CRMO with a systemic disease. The diagnosis was challenging in view of the raised inflammatory markers and purulent drainage. It has been less frequently described in UC compared to Crohn’s disease. CRMO is a relatively rare autoinflammatory non-infectious bone disorder condition. It can be idiopathic (as in Case 1) or associated with systemic diseases (as in Case 2). There is a wide spectrum of clinical presentations. With the exception of Majeed syndrome, CRMO is a diagnosis of exclusion as there is no specific diagnostic laboratory test. Jansson and Bristol criteria can aid in the clinical diagnosis. Often there may be a delay in diagnosis. One study showed a median interval of 15 months between symptom onset and diagnosis. The characteristic radiologic finding of CRMO consists of osteolytic lesions with surrounding sclerosis. A nuclear bone scan may be needed to assess subclinical and multi-focal involvement. A bone biopsy may be required to exclude an infectious or neoplastic etiology. Treatment may include NSAIDs, corticosteroids, methotrexate, bisphosphonates, and biologics.
Conclusions: The diagnosis of CRMO requires a co-management team approach between the hospitalist, orthopedic surgeon, pathologist, radiologist, and rheumatologist. A high index of suspicion is required to minimize the number of unnecessary interventions in the form of repeated biopsies, repeated radiation exposure due to repeated x-rays or nuclear scans, and prolonged antibiotics.