脳腫瘍に合併したカリニ肺炎に関する検討

Pneumocystis Carinii Pneumonia Complicating Brain Tumor

　Ⅰ．はじめに

脳腫瘍の治療において，併存する脳浮腫に対し経口ステロイド剤が投与される症例は少なくない．しかしながら，長期ステロイド剤投与の合併症であるカリニ肺炎についてはあまり知られていない．脳腫瘍に対するステロイド投与に合併したカリニ肺炎については，海外ではこれまでにいくつか報告されているが^4,12,14)，本邦での詳細な報告はなく，その特徴や危険因子についてもあまり知られていない．

　Pneumocystis cariniiはヒトの肺に常在する病原体で，真菌に近いと考えられている．細胞性免疫の低下した状態において間質性肺炎を来し，特に免疫抑制剤治療中の患者やacquired immunodeficiency syndrome（AIDS）においては最も重要な日和見感染症の一つである．

　われわれは1994年から2002年の9年間に当科で経験した12例の脳腫瘍に合併したカリニ肺炎の症例を経験したので，その特徴,危険因子について検討した．

　Brain tumors are frequently treated with steroids due to the presence of peritumoral edema. However,in Japan,it is not widely recognized that primary brain tumor patients who are receiving steroid therapy become susceptible to Pneumocystis carinii pneumonia (PCP). We reviewed the clinical features and risk factors for PCP in brain tumor patients treated at our institution between 1994 and 2002.

　The treated cases consisted of 6 men and 6 women ranging in age from 47 to 78yr (mean age 65.3). Underlying diseases included malignant glioma in 9 patients,malignant lymphoma in 2 patients and meningioma in one patient. All were diagnosed by respiratory disease specialists using bronchial washings and bronchoalveolar lavage or chest X ray/CT image. Radiation therapies were administered with 20 to 60 Gy (mean 52.9 Gy) except in one patient. Chemotherapy was performed with ranimustine in 4 malignant glioma patients and with methotrexate in 2 malignant lymphoma patients. Prednisone,begun perioperatively,was reduced gradually from a mean initial dosage of 38.3mg/day orally. The duration of steroid treatment at the onset of PCP in these patients ranged from 41 to 79 days (mean 61.4days).

　Six patients (50%) died of PCP despite appropriate antibiotic therapy and 2 patients needed intensive therapy with a respirator.

　For early diagnosis of PCP,periodic serological (eg ; the level of lactate dehydrogenase and β-D-glucan) and radiological examination (eg ; chest X ray and CT image) is indicated in patients with brain tumors,and prophylaxis against PCP might be needed for patients with intracranial neoplasms and who are also receiving high-dose and long-term steroid treatment.