症例は42歳女性．29歳時骨髄異形成症候群のため同種骨髄移植．40歳時より呼吸困難出現．胸部CT上両側肺野容積減少，胸膜下に浸潤影を認めたが蜂巣肺は認めず．臨床経過，特徴的な身体所見，画像所見より特発性上

Around 30% of cases of spontaneous intracerebral hemorrhage (ICH) occur in patients taking antithrombotic drugs (i.e., oral antiplatelet drugs and oral anticoagulants). However, antithrombotic drugs themselves are not a direct cause of vascular structure disruption, and only promote and/or prolong bleeding from vulnerable arterioles with pathology such as microaneurysms or fibrinoid necrosis, which are characteristics of cerebral small vessel diseases (SVDs). Thus, to a substantial degree, SVD, which is caused by aging, hypertension, or cerebral amyloid angiopathy (CAA), is the true cause of spontaneous ICH. Cerebral microbleeds (CMBs) are prone to bleeding and cause most spontaneous ICH. CMBs may thus be a specific and promising neuroimaging biomarker of SVDs and a clinically useful predictor of antithrombotic drug–related ICH. Such a relationship raises concerns about the increased ICH risk due to administration of antithrombotic drugs in patients with CMBs. Since 2017, several studies suggested some answers to this issue, and at this time, no evidence shows that the presence or number of CMBs on MRI can determine the pros and cons of antithrombotic therapy. A remaining major issue is validation of the risks and benefits of antithrombotic therapies for patients with CAA–related ICH. As a local issue, determining whether antithrombotic therapy for patients with a large number of CMBs is beneficial in East Asians will be necessary. East Asians are considered to be prone to hypertensive SVDs. Some of these issues will be clarified by an ongoing Japanese prospective, multicenter, observational study called “The Bleeding with Antithrombotic Therapy Study 2”, which enrolled patients with cerebrovascular or cardiovascular diseases who were taking oral antithrombotic agents.

症例は49歳，男性．5年前に当院血液内科で同種造血幹細胞移植を施行されている．移植後の経過は良好で慢性GVHD（graft-versus-host disease）もなく，画像検査は移植後1年目に施行されたのが最終であった．2ヵ月ほど前から労作時呼吸苦を自覚するようになり，右気胸を発症して当科紹介受診となった．こちらは胸腔ドレナージと胸膜癒着術のみで軽快したが，その3ヵ月後に左気胸も発症し，難治性肺瘻であったので手術を施行した．背景に上葉優位型の肺線維症が存在しており，造血幹細胞移植後晩期の非感染性呼吸器合併症の可能性が考えられた．近年，稀ではあるが造血幹細胞移植後に上葉優位型肺線維症を発症する報告が散見されるようになっているものの，慢性GVHDとの関連性は示されておらず，発症機序は明らかにされていない．今後も症例の蓄積が必要と思われるため，文献的考察を加えて報告する．