Interstitial Pneumonia Associated with the Influenza Vaccine: A Report of Two Cases

Hibino, Makoto; Kondo, Tetsuri

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/mm 3 ) with normal white blood cell differentiation. Blood chemistry showed no abnormalities, including a normal lactate dehydrogenase (LDH) level. Serological tests revealed the following: Creactive 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. Transbron-Department of Respiratory Medicine, Shonan Fujisawa Tokushukai Hospital, Japan chial 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%).