大動脈炎症候群で副腎皮質ステロイド薬内服中に重症麻疹肺炎を発症した1成人例

Measles Pneumonitis in an Adult Patient with Aortitis Syndrome Receiving Long-term Glucocorticoid Therapy

　患者は31歳，男性．大動脈炎症候群で副腎皮質ステロイド薬を内服中，39℃の弛張熱が続いた．その後，体幹部と顔面に皮疹を認め，急激な間質性肺炎陰影（両肺野の斑状・網状陰影）および呼吸困難が出現し，高度な低酸素血症を認め麻疹肺炎と診断された．直ちに気管内挿管し，人工呼吸管理を行った．副腎皮質ステロイド薬によるパルス療法とγ-グロブリンおよびビタミンAの投与を行った．肺胞—動脈血酸素分圧較差の増大がみられ，吸気中酸素分画0.8〜0.9で呼気終末陽圧を加えても動脈血酸素分圧の上昇は不十分で治療に難渋した．しかし，肺炎陰影像は次第に回復し，約4週後に抜管でき後遺症なく退院した．成人麻疹肺炎は致死率が高く，有効な治療法の報告も少なく，本症例のように副腎皮質ステロイド薬内服中に発症した例に同薬のパルス療法が効果を示すかも不明である．免疫機能の低下している例で麻疹の罹患歴や予防接種歴のない不明熱を診た際には，麻疹のみならず麻疹肺炎への進行も考慮し，動脈血酸素飽和度モニタリングを行い，診断されれば人工呼吸管理や副腎皮質ステロイド薬パルス療法などの速やかな対処が必要と考えた．

A 31-year-old male patient under long-term glucocor-ticoid therapy for aortitis syndrome showed remittentfever of more than 39℃. Seven days after the high feverphase, the patient showed typical clinical signs ofIneasles, and then developed progressive respiratoryfailure with severe hypoxemia. Chest radiographyshowed bilateral diffuse nodular and reticular shadowscompatible with measles pneumonitis.The patient wasintubated and underwent artificial respirator control.Steroid pulse therapy (methylprednisolone,1000 mg/dayfor 3 days) combined with vitamin A and gamma-globulin was started immediately. Although the patientshowed a significantly increased A-a O₂ difference, hishypoxemia gradually resolved after the combinationtherapy, and he was successfully weaned from the respi-rator 24 days after intubation without complications.We believe that arterial blood oxygen saturationmonitoring is important for early diagnosis of measlespneumonitis, and that steroid pulse therapy combinedwith vitamin A and gamma-globulin may be effectivefor adult patients with immuno-compromised condi-tions.