胸腔鏡下に摘出した遺伝性球状赤血球症による胸腔内髄外造血巣の1例

Video-assisted thoracoscopic surgery for thoracic extramedullary hematopoiesis in a case of hereditary spherocytosis

◆要旨：胸腔鏡下に摘出した遺伝性球状赤血球症による胸腔内髄外造血巣を経験したので報告する．症例は既往歴のない54歳，男性．健診で胸部異常影を指摘され，精査で後縦隔腫瘍と診断された．2年間で軽度増大傾向を認め，その頭側に娘結節の出現を認めたため切除の方針となり，胸腔鏡下に腫瘍を摘出し，病理で髄外造血巣と診断された．髄外造血巣は貧血を背景に発生することが多く，血液疾患の合併が疑われた．術後に精査し，遺伝性球状赤血球症と診断した．胸腔内髄外造血巣は稀な疾患ではあるが，後縦隔腫瘍の鑑別疾患として考慮されうるものである．切除後に髄外造血巣の診断が得られた場合には，背景に血液疾患を疑い精査する必要がある．

　We retrospectively reviewed a case of video-assisted thoracoscopic surgery （VATS） for thoracic extramedullary hematopoiesis （EMH） due to hereditary spherocytosis with some literature. A 54-year-old male was admitted to our hospital for an abnormal shadow detected by a chest X-ray film. Computed tomography （CT） scan revealed a mass shadow in his posterior mediastinum, the size was 26mm. We diagnosed the lesion as a neurogenic tumor, and he was followed up. The tumor had been gradually enlarging, and daughter nodule appeared, therefore complete resection by VATS was performed. Histological diagnosis was EMH. Depending on the pathological diagnosis, we suspected some underlying hematologic disorders. Hereditary spherocytosis was identified by hematologic examination after surgery. EMH is defined as hematopoiesis occurring in organs outside of the bone marrow. It occurs if the bone marrow is no longer functional, and it is detected in a number of hematological diseases. EMH is very rare tumor as a posterior mediastinal tumor, and needle biopsy has a risk of hemorrhage. Therefore, to make a diagnosis of EMH is difficult without surgical resection. We could safely achieve complete resection by VATS and identify hereditary spherocytosis after the operation. Various hematological diseases must be taken into consideration when posterior mediastinal tumor was diagnosed as EMH.