診断に長期を要した上腕骨遠位部類骨骨腫の1例

Osteoid Osteoma of Distal Humerus Requiring Long Time for Diagnosis. Case Report

　症例は16歳の男性で，14歳時から右肘関節痛を自覚した．テニス肘と診断され，MRI検査などを受けたが2年6カ月間もの長期にわたり確定診断に至らず，当院を紹介され受診となった．CTで上腕骨滑車部分にnidusを認め，上腕骨遠位部類骨骨腫の診断で腫瘍摘出術を行った．病理診断は類骨骨腫であり，疼痛は消失し，術後2年の現在，再発は認めていない．長期に及ぶ関節痛を訴える患者ではMRIがCTよりも先に撮影されることが多い．しかし類骨骨腫を念頭に置かなければMRIを撮影していても本症例のように見逃される可能性がある．

　We report the case of a 16-year-old male with osteoid osteoma of the distal humerus.　At 14 years of age he presented at a nearby hospital with pain in his right elbow and was diagnosed with tennis elbow.　Non-steroidal anti-inflammatory drugs were prescribed, but his elbow pain persisted.　He consulted 4 other hospitals, and magnetic resonance imaging was performed, but no definitive diagnosis was reached.　At 16 years of age he came to our hospital, A radiography revealed a radiolucent area in the trochlea of the humerus and a CT scan showed a nidus lesion in the same area.　Based on these findings we made a diagnosis of osteoid osteoma of the distal humerus, and surgically removed the tumor.　The final pathology report comfirmed the diagnosis.　At the 18-month follow-up examination, the patient was pain-free and had a full range of motion in his elbow.　Our experience with this case suggested that osteoid osteoma must be included in the differential diagnosis even when interpreting MRI findings in a patient with longstanding articular pain.