非定型抗酸菌（Mycobacterium avium complex）による橈骨骨髄炎の1例

Osteomyelitis of the Radius Caused by Atypical Mycobacterium (Mycobacterium Avium Complex) : Case Report

　抄録：非定型抗酸菌による右橈骨骨髄炎の1例を経験したので報告する．症例は65歳，男性，職業は植木職人であった．主訴は左前腕部痛，腫脹で，特に誘因なく左前腕部痛が出現し腫張，肘関節運動時痛に気付いたため当科を初診した．初診時，左前腕近位部に腫脹，熱感，圧痛を認め，血液学的検査で軽度の炎症反応がみられた．単純X線像では橈骨粗面レベルにおいて空洞状骨吸収像，MRIではT1強調像で橈骨骨髄近位部に低信号域，T2強調像で等～高信号域の混在がみられた．観血的生検では橈骨髄内に膿の貯留があり，培養の結果非定型抗酸菌（Mycobacterium aviumcomplex）と同定された．4剤併用化学療法を施行するも手術創部より瘻孔形成，膿排出がみられたので，再手術時に掻爬とともに自家腸骨移植を行った．その後，リファンピシン，クラリスロマイシン，サイクロセリンの投与にて症状軽快し経過良好である．

　Atypical mycobacterial osteomyelitis is rare. We report a case of osteomyelitis of the radius caused by atypical Mycobacteria (Mycobacterium aviumcomplex). A 65-year-old man was admitted to our hospital, presented with painful and swelling of the left forearm. Laboratory findings included a leukocyte count of 9,000, erythrocyte sedimentation rate of 59mm/h, and a positive C-reactive protein value. Radiographs of the left elbow revealed an osteolytic lesion of the radial tuberosity. Standerd tuberculin skin test was negative. At surgery, an abscess was removed, and cultures of the lesion yieldedmycobacterium aviumcomplex. Antitubercular drug therapy consisting of rifampicin, clarithromycin, and cycloserine was continued postoperatively. But, one month later, fistula developed at the site of the incision, and curettage and bone graft were performed. The antitubercular drug therapy was continued postoperatively and nine months later, his condition is favorable.