A 25-year-old man was referred to our hospital with a 10-year history of bilateral upper lung fibrosis. He had had asthma since the age of 2 years. He never smoked and had no occupational or environmental exposure. At the age of 19 years, he underwent a fiber-optic bronchoscopy examination at another hospital. However, at that time, TBLB specimens stained with hematoxylin and eosin (HE) did not allow any specific diagnosis. Since then, he has visited the hospital once a year for a medical check-up. Although he was asymptomatic, the lung fibrosis progressed gradually. He was then referred to our hospital.
On physical examination, he was slender with a body mass index (BMI) of 15.1 kg/m2 and had no clubbed fingers. Respiratory sounds were normal. A chest radiograph at the age of 15 years showed upper lung-dominant fibrotic opacities with elevated hilar opacities. Ten years later, upper lung fibrosis had worsened with markedly increased hilar opacities (Fig. 1a). A chest computed tomography (CT) taken at our hospital showed a flattened chest cage and subpleural consolidations with traction bronchiectasis located in the bilateral upper lung fields (Fig. 1b). By contrast, the lower lung fields were almost normal. Spirometry showed markedly restrictive impairment: forced vital capacity (FVC) was 1820 mL (43.5% pred.). Serum Krebs von den Lungen-6 (KL-6) concentration was near the upper limit of the normal range (470 U/mL), and Surfactant protein-D (SP-D) concentration was markedly increased (531 ng/mL).
The slender constitution with flattened chest cage and the long history of upper lung lesions with restrictive impairment raised the possibility that the disease was PPFE. We obtained the previous biopsy specimens stained with HE and the paraffin blocks, and additional histological specimens stained with Elastica van Gieson (EVG) were prepared to identify elastofibrosis. The EVG specimen revealed dense elastosis just beneath the subepithelial reticular basement membrane of the peripheral airway (Fig. 1c, d). Another specimen showed that alveoli were filled with collagen in association with septal elastosis. All of these histological findings are consistent with those of PPFE.
b. Upper lung fields of chest CT in case 1.