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TAFRO 症候群を模倣した播種性 Mycobacterium genavense 感染症
Disseminated Mycobacterium genavense infection mimicking TAFRO syndrome.
PMID: 32684386 DOI: 10.1016/j.jiac.2020.06.020.
抄録
TAFRO 症候群は、特発性多中心キャッスルマン病の稀な変種であり、播種性非結核性マイコバクテリア（NTM）感染を除外しなければならない。しかし，非結核性マイコバクテリアの増殖が遅いため，病原体の同定は困難な場合が多い．本稿では，播種性Mycobacterium genavence感染症の1例を紹介する．症例は69歳の日本人男性で，背中と肋骨の疼痛を伴う長期発熱を呈した．全身検査の結果，血小板減少，アルカリホスファターゼ上昇，胸水・腹水アナサルカ，骨髄巨核球症，肝腫大を認めた．磁気共鳴画像（MRI）では椎体にびまん性のT1およびT2低強度の斑状病変が認められたが，生検では結論は得られなかった．この患者はTAFRO症候群の診断基準を満たしており、プレドニゾロンの投与が開始されたが、その後まもなく全身状態は改善した。42日培養後の血液培養でMycobacteriumの存在が確認されたが，従来のアガーには菌が繁殖していなかったため，この時点ではコンタミネーションと考え，退院した。マイコバクテリウム分離から10週間後に持続的な発熱を発症し、再入院となった。この時、椎骨アオイの生検で大量のマイコバクテリウムが確認され、後にシークエンシング解析によりM.genavenseと同定されることに成功した。播種性M.genavense感染との最終診断のもと，クラリスロマイシン，リファンピシン，エタンブトールによる治療を行った．本症例は，播種性M.genavense感染症がTAFRO症候群と同様の臨床経過をたどる可能性を示唆するものであった．
TAFRO syndrome is a rare variant of idiopathic multicentric Castleman's disease, for which disseminated non-tuberculous mycobacteria (NTM) infection must be excluded. However, due to the slow and fastidious growth of the organisms, identification of the pathogen is often challenging. We herein describe a case of disseminated Mycobacterium genavence infection, in which manifestations of the patient were confusingly similar to those of TAFRO syndrome. A 69-year-old Japanese man presented with prolonged fever accompanying pain in his back and ribs on the right side. Systemic investigations revealed thrombocytopenia, marked elevation of alkaline phosphatase, anasarca (pleural effusion and ascites), megakaryocytosis in the bone marrow, and hepatomegaly. Magnetic resonance imaging (MRI) showed diffuse, T1-and T2-low-intensity spotted lesions on his vertebral bodies, but biopsy showed inconclusive results. The patient met the diagnostic criteria of TAFRO syndrome and was started on prednisolone, which improved his general condition shortly thereafter. Blood culture after 42 days of incubation revealed the presence of Mycobacterium; however, we considered it a contamination at that time because no organisms grew on conventional agars, and the patient was discharged. Ten weeks after the isolation of Mycobacterium, he developed persistent fever and was readmitted. This time, vertebral bone mallow biopsy demonstrated a large amount of mycobacterium, which was later successfully identified as M. genavense by sequencing analysis. Under a final diagnosis of disseminated M. genavense infection, we treated the patient with clarithromycin, rifampicin, and ethambutol. This case highlighted that disseminated NTM infection may follow a similar clinical course as that of TAFRO syndrome.
Copyright © 2020 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.