長期追跡した慢性再発性多巣性骨髄炎（CRMO）の1例

Chronic Recurrent Multifocal Osteomyelitis in Childhood ; Radiological and Clinical Investigations during a Long-Term Follow-Up : Case Report

　抄録：慢性再発性多巣性骨髄炎（chronic recurrent multifocal osteomyelitis，以下CRMO）の1例を70カ月間の画像所見を中心に報告する．症例は左膝痛を主訴とする初診時14歳の女児である．初診時の単純X線像では，左けい骨近位骨幹端の線維性骨皮質欠損の他に異常はなかった．症状は一時消失したが初診から23カ月時に再発し，単純X線像で左けい骨近位骨幹端に溶骨像と硬化像を認めた．骨シンチグラフィーでは左けい骨近位部の他，左けい骨遠位部，仙椎に異常集積を認めた．左けい骨から生検を施行したが起因菌は検出されずCRMOと診断した．非ステロイド性消炎鎮痛剤により症状は消失したが，39カ月時にはけい骨近位部は著明な硬化性骨肥厚を呈するに至った．60カ月時に骨髄炎が再発したが，70カ月時には軽快した．診断確定に最も重要なのはCRMOという疾患概念を認識しているか否かである．CRMOは長い経過をたどり，小児では局所的予後が必ずしも良好とは限らないので注意を要する．

　［Objective］ To describe the clinical and radiological outcome after 70 months of follow-up of a case of chronic recurrent multifocal osteomyelitis (CRMO). ［Patient and Course］ A 14-year-old girl presented with pain in the left knee after jogging. Radiographs showed no abnormalities except a fibrous cortical defect in the proximal tibia, and her symptoms improved spontaneously. Twenty-three months after the initial presentation, she returned with pain and swelling in the proximal portion of the left lower leg. Radiographs showed an osteolytic and sclerotic lesion in the proximal tibial metaphysis. The CRP value was negative, but the erythrocyte sedimentation rate was elevated, and the bone resorption markers had increased significantly. Bone scintigraphy revealed abnormal uptake in the left proximal tibia, distal tibia, and sacrum. Based on the pathological and microbiological findings, a diagnosis of CRMO was made. Nonsteroidal anti-inflammatory drugs (NSAIDs) were effective and well tolerated, and at 39 months after the onset of symptoms radiographs showed purely sclerotic hyperostosis in the left proximal tibia. At 60 months of follow-up, the patient again complained of left knee pain, and radiographs showed recurrence of the osteomyelitis. At present, 70months after the initial presentation, the patient remains asymptomatic and has not developed any additional bone lesions. ［Conclusions］ A correct diagnosis of CRMO depends on recognition of this condition. The long-term prognosis of CRMO remains unclear, however, CRMO is not always a benign condition in children.