As part of her physical examination 17 months ago, a 58-year-old woman underwent chest computed tomography (CT), which showed no abnormalities. Six months ago, she began to experience a persistent cough and dyspnea, for which she was prescribed 20 mg of prednisolone, but there was no response. Then, she was prescribed concomitant cyclosporine, but her condition worsened. The patient was admitted to our hospital for examination. She had no past medical history or family history of PAP, and she did not smoke, but she was taking estradiol and raloxifene to prevent menopausal disorders.
The patient's physical examination revealed the following: height 155 cm, weight 44.3 kg, temperature 36.6  C, blood pressure 150/101 mmHg, radial pulse 100 bpm, respiratory rate 14 bpm. Fine crackles were heard in both lungs. Lactate dehydrogenase (250 IU/L), Krebs von den Lungen-6 (KL-6 1329 U/mL), and lung surfactant protein D (211.5 ng/mL) levels were elevated. Arterial blood gas analysis in room air showed no hypoxemia (partial pressure of oxygen, 91.1 torr), and respiratory function tests revealed no abnormalities. Chest CT showed bilateral ground-glass opacities and reticular shadows, mainly distributed in the lower lobes. The abnormal shadows tended to enlarge over time after the initial examination (Fig. 1).
Neither findings nor history were suggestive of hypersensitivity pneumonia, drug-induced pneumonia, eosinophilic pneumonia, or collagen vascular disease. Idiopathic interstitial pneumonia, including nonspecific interstitial pneumonia (NSIP), was suspected. Bronchoalveolar lavage was performed in the superior lingular segment of the left lobe, followed by a transbronchial lung biopsy (TBLB) of the left lower lobe. The BALF was transparent and did not have a milky appearance. The BALF cell count was unremarkable. The biopsy specimens contained eosinophilic bodies that strongly stained with periodic acid-Schiff (PAS) staining (Fig. 2).
The serum level of anti-granulocyte macrophage colony-stimulating factor (anti-GM-CSF) antibody was high at 74.0 U/mL (normal level <1.7). Based on these findings, the diagnosis of APAP was confirmed.