2023 年 1 巻 2 号 p. 101-104
Acute fibrinous and organizing pneumonia (AFOP) is a rare interstitial lung disease histologically characterized by massive intra-alveolar fibrin deposition without a hyaline membrane and eosinophilic infiltration. We report a case of idiopathic AFOP with golden-yellow bronchoalveolar lavage (BAL) fluid. The histological examination of the transbronchial lung biopsy specimen demonstrated massive fibrinous exudates in most of the alveolar spaces. The golden-yellow BAL fluid was thought to be due to the intense exudation of the plasma components into the alveoli. The cellular fractionation of the BAL fluid showed 47% neutrophils, 36% lymphocytes, 11% macrophages, and 5% eosinophils, combining features of diffuse alveolar damage (DAD) and cryptogenic organizing pneumonia (COP). The patient showed rapid clinical improvement with prednisolone therapy, although the AFOP relapsed during the tapering of prednisolone, and required cyclosporine in addition to prednisolone. AFOP is considered a condition between DAD and COP and might not follow a single disease concept. Golden-yellow BAL fluid might be useful for differentiating AFOP from COP.
