A 53-year-old Japanese female with a history of cervical cancer and vocal cord papilloma visited to our hospital for evaluation of three weeks history of progressive dry cough and dyspnea. She was a past smoker (1 pack/day for 8 years) and had no history of environmental exposure. Although she was treated with azithromycin as an outpatient, she presented with right chest pain, fever and hemoptysis on three days after the first visit and admitted to our hospital.
On hospital admission, her vital signs were as follows: heart rate 125 bpm, blood pressure 114/81 mmHg, body temperature 39.0  C. Percutaneous arterial blood oxygen saturation was 94% on room air and respiratory rate was 24/min. Chest examination revealed unilateral coarse crackles in the right lower lung fields. Skin rash, joint pain and swelling, muscle weakness, and other physical findings suggestive of connective tissue disease were not observed. Laboratory testing on admission showed a white blood count of 11,180/muL, hemoglobin of 14.2 g/dL and platelet count of 327,000. Erythrocytes sedimentation rate was 98 mm/h and C-reactive protein was 5.3 mg/dL. Lactate dehydrogenase, Krebs von den Lungen-6 and surfactant protein D were within the normal range. Work up for respiratory disease including sputum cultures, urinary pneumococcal and Legionella antigen were all negative. Serologic studies for connective tissue disease, vasculitis were also unrevealing.
High-resolution computed tomography (CT) of the chest revealed unilateral focal consolidation with halo sign in the right lower lobe (Fig. 1A-D).
Despite that ceftriaxone and minocycline were started on the first day, her clinical condition did not improve. On the third day of admission, the patient underwent flexible bronchoscopy with bronchial wash and TBLC from the right lower lobe B9 and B10. The biopsy specimens of 4 mm x 5 mm size were collected by TBLC. Histological study of these specimens showed intra-alveolar fibrin balls, involving more than three quarters of alveolar space and mononuclear cells infiltration without eosinophils and formation of hyaline membranes (Fig. 2A-C), indicating AFOP. Bacterial culture was negative.
After TBLC, high dose of methylprednisolone was initiated, resulting in rapid clinical improvement. On the twenty five day of admission, she was discharged home on 25 mg prednisone daily. She has remained free of pulmonary symptoms and finished taking prednisone ten months later. There was no evidence of collagen tissue disease, vasculitis, and other etiology during the disease course. We diagnosed her with idiopathic AFOP.