持続する咳嗽，発熱を初発症状とした浸潤型胸腺腫の1例—当院における胸腺腫手術例のまとめ

A Case of Invasive Thymoma with an Initial Symptom of Persistent Cough and Fever

　症例は75歳，男性．主訴は持続する湿性咳嗽，発熱．1994年1月上旬より主訴を認め近医を受診した．投薬を受けたが，臨床症状および血液学的炎症所見が改善しないため，当院を紹介され入院となった．胸部単純X線写真では明らかな異常所見を認めなかったが，血沈，白血球，CRPの高値を認めた．胸部CTスキャンにて前縦隔に辺縁不整な腫瘤陰影を認めた．MRIでは同部に辺縁不整な軟部腫瘍を認め，T2強調像では内部信号強度が不均一であった．以上より浸潤型胸腺腫を疑い，腫瘍摘出術を施行し，左肺S³，心嚢，無名静脈への浸潤を伴う胸腺腫（リンパ球優位型）と診断した．持続する感冒様症状に対して鑑別診断として縦隔腫瘍も考慮することが必要であり，胸部CTスキャンおよびMRIの有用性が示唆された1例である．

A 75-year-old man was admitted to our hospital because of persistent productive cough and fever. Although his chest X-ray film showed no abnormal finding, the laboratory data showed elevated values of erythrocyte sedimentation ratio, white blood cell counts and CRP. There was a soft tissue density mass in the anterior mediastinum on chest CT. There was an irregular mass adjacent to the ascending aorta with no fat tissue layer on MRI. On the T2-weighted images, there was inhomogeneous intensity of signal level in thetumor, suggesting invasive thymoma. In the macro-scopic findings during the operation, thymoma was found to have invaded the left S³, the pericardium and the innominate vein. Pathological examination revealed the thymoma to be predominantly lymphocytic in type. After the thymoma was removed. the patientwas relieved from cough and fever. This case suggested that chest CT and MRI are useful for the pathological diagnosis of thymoma.