Two series of familial cases with unclassified interstitial pneumonia with fibrosis

Abstract

Several children presenting with mild symptoms of respiratory tract infection were diagnosed with unclassified interstitial pneumonia with fibrosis. Their clinical and radiological findings were similar to those of acute interstitial pneumonia, but there were some differences in the pathological findings. Unclassified interstitial pneumonia with fibrosis is characterized by histological findings of centrilobular distribution of alveolar damage and bronchiolar destruction with bronchiolar obliteration. This report describes two different series of familial cases of unclassified interstitial pneumonia with fibrosis, which developed almost simultaneously in the spring. Some of the individual cases showed rapidly progressive respiratory failure of unknown cause, with comparable clinical courses and similar radiological and pathological features, including lung fibrosis. Each family member was affected almost simultaneously in the spring, different kinds of viruses were detected in two patients, and all members were negative for bacterial infection, environmental and occupational agents, drugs, and radiation. These findings implicate a viral infection and/or processes related to a viral infection, such as an exaggerated or altered immune response, or an unknown inhaled environmental agent in the pathogenesis of unclassified interstitial pneumonia with fibrosis.

Keywords: Interstitial pneumonia; environment; family; fibrosis; respiratory tract infections.

Fig. 1

Chest radiography and biopsy specimens for Case 1. Chest radiography (A) on day 2 of the exacerbation of cough and dyspnea. Chest computed tomography (CT) scan (B) on admission revealed the presence of ground-glass attenuation with diffuse centrinodular opacity in both lungs. Pre-discharge chest radiography (C) and chest CT (D) showed a reduction in the extent of ground-glass opacities in both lungs. Biopsy specimens (E) obtained on day 14 of the exacerbation of symptoms. Alveolar pneumocyte hyperplasia (arrow) and interstitial fibroblastic proliferation are features consistent with the organizing phase of diffuse alveolar damage. Bronchioles are destructed and obliterated by fibroblastic proliferation (asterisk). (Hematoxylin and eosin staining, ×200 magnification)

Fig. 2

Findings for Case 3. Chest radiography (A) and chest computed tomography scan (B) revealed the presence of an extensive pneumomediastinum, a pneumothorax of the right lung, and diffuse ground-glass opacities and consolidation in both lungs. Follow-up chest radiography on day 72 of admission revealed an increased level of bilateral infiltrates (C). Histological section (D) obtained from a postmortem biopsy showed extensive interstitial fibrosis with hyperplastic type II pneumocytes and hyaline membrane formation, suggesting the fibrotic phase of diffuse alveolar damage. Bronchiolar destruction and mild bronchiolar obliteration are present. (Hematoxylin and eosin staining, ×400 magnification)