成人発症型Still病を疑われたインターロイキン6産生左房粘液腫の1例

A Case of IL-6-producing Left Atrial Myxoma, which was Diagnosed as Adult Still's Disease

　患者は50歳，男性．37℃台の持続する発熱を主訴に近医を受診した．持続する発熱，発疹の出現，自己抗体がすべて陰性であったこと，感染症，悪性腫瘍の否定から，不明熱の原因を成人発症型Still病と診断され，非ステロイド性抗炎症薬の投与を受けていた．また，同時期に動悸を自覚し心エコー検査を受けたところ，心内に腫瘤を指摘され当センターへ紹介された．腫瘤は左房粘液腫が疑わしく，不明熱の原因が左房粘液腫であると判断し，腫瘍摘出術を施行した．術前に29.7pg/mlと高値を示していた血清インターロイキン6（IL−6）値は，術後急激に低下した．また，発熱，炎症などの臨床症状は改善した．以上よりIL−6産生左房粘液腫が考えられた．IL−6産生左房粘液腫は不明熱を鑑別する上で大切な疾患であると思われた．

　The patient was a 50-year-old man. He was admittedto a local hospital with fever of unknown origin. Hisdiagnosis was adult type of Still's disease. He wasadministered a nonsteroidal anti-inflammatory drug.Since he had the symptom of palpitation, he underwentan echocardiography. The echocardiogram demonstrated a mass in the heart. It was then that he was referredto our medical center. The mass was diagnosed as leftatrial myxoma and surgical resection was performed.Preoperatively his serum IL-6 level was 29.7pg/ml, andit decreased drastically after the operation. His symptoms disappeared after surgery, but his left atrialmyxoma was considered to be producing IL-6. Webelieve that left atrial myxoma with associated production of IL-6 is an important disease as a differentialdiagnosis for fever of unknown origin.