In December 2014, a 71-year-old Japanese woman presented with severe, dry cough and left chest pain. She had received the seasonal influenza vaccine at another clinic 36 days before visiting our clinic, and the local injection site reaction was mild. She developed a dry cough the following day, and it gradually worsened. Two days before the first visit, she developed left chest pain. Her medical history revealed well-controlled diabetes mellitus and dyslipidemia. She had undergone right nephrectomy for renal tuberculosis 37 years ago and had been prescribed rosuvastatin and linagliptin for the past 12 months.
At the first visit, all her vital signs and physical features were normal. A complete blood count revealed mild leukocytosis (white blood cell count, 11,400/mm3) with normal white blood cell differentiation. Blood chemistry showed no abnormalities, including a normal lactate dehydrogenase (LDH) level. Serological tests revealed the following: C-reactive protein (CRP), 5.54 mg/dL; soluble interleukin-2 receptor (sIL-2R), 1,086 U/mL; and surfactant protein-D, 178.2 ng/mL. Her serum surfactant protein-A (SP-A) and Krebs von den Lungen-6 (KL-6) levels were normal. Chest roentgenography (Fig. 1A) and computed tomography (Fig. 1B) showed patchy, peribronchial consolidations with air bronchograms and ground-glass opacities without pleural effusion in both lungs. Electrocardiogram and ultrasonic echocardiogram were normal. The severe cough followed by musculoskeletal chest pain precluded pulmonary function tests. Bronchoalveolar lavage fluid (BALF) examination revealed 65% lymphocytes, 15% eosinophils, 19% macrophages, and 1% neutrophils, with no infectious organisms or malignant cells. The CD4+/CD8+ ratio was 2.1. Transbronchial lung biopsy revealed lymphocytic alveolitis and granulation tissue plugs within airspaces, suggesting organizing pneumonia (Fig. 1C). A drug lymphocyte stimulation test (DLST) performed using peripheral lymphocytes showed a positive reaction to the influenza vaccine, with a stimulation index of 190% (normal, <180%).
Oral prednisolone at 35 mg (0.8 mg/kg/day) was administered daily, and within a week, our patient's symptoms and abnormal radiography and laboratory findings began resolving. We then performed pulmonary function tests and found a forced vital capacity (FVC) of 2.07 L (normal, 79.6% predicted), forced expiratory volume in 1 s (FEV1) of 1.68 L (normal, 88.0% predicted), and an FEV1/FVC ratio of 81.1%. Oral steroid therapy was tapered on an outpatient basis. Ten months after the treatment, her prednisolone dose was tapered. The patient remains healthy with no further symptoms or radiographic abnormalities (Fig. 1D), and she did not receive the annual influenza vaccine the following year.