[Follicular bronchiolitis: report of 3 cases and literature review].

Objective To improve understanding of the characteristics of follicular bronchiolitis(FB). Methods The clinical data of 3 patients with FB confirmed by thoracoscopic lung biopsy were retrospectively analyzed. A literature search was performed with "follicular bronchiolitis" as the key word in China Knowledge Resource Integrated Database, Wanfang and PubMed, Ovid Database. The time interval was from January 1947 to December 2015. Related articles of FB were retrieved and the clinical, radiographic characteristics and prognosis were analyzed. Results Among the 3 patients, 1 was male and 2 were female, aging 32-55 years. Two patients were asymptomatic, and 1 patient presented with fever, cough and dyspnea. Two patients showed normal pulmonary ventilatory function with decreased diffusive function, and 1 patient showed normal pulmonary function. The predominant HRCT findings were bilateral multiple small nodules and cystic opacities, patchy ground-glass opacities, reticular opacities and traction bronchiectasis. The pathological examination by thoracoscopic biopsy revealed bronchiolar and peribronchiolar lymphoid follicles. All patients were treated with corticosteroids, with 2 patients receiving immunosuppressants. Follow-up HRCT after 1-2 months showed no improvement, and further follow-up HRCT after 2-4 years revealed no change in 2 patients while the other patient had increased pulmonary nodules and cystic opacities. Seventeen articles concerning FB with complete records were included in the literature review. A total of 64 patients were reported in these articles. The typical images were bilateral multiple small nodules and ground-glass opacities, reticular opacities, and cystic opacities. The majority of patients improved after treatment of corticosteroids and (or) immunosuppressants. But our 3 cases showed no improvement. Conclusions FB is a rare small airway disease which has non-specific clinical manifestations and pulmonary function. The most common imaging findings are bilateral multiple small nodules, with cystic opacities, ground-glass opacities, and reticular opacities. Surgical thoracoscopic biopsy can get ideal specimen which is useful for diagnosis. The curative effects of corticosteroids or immunosuppressants on FB need to be further clinically investigated. Key words: Follicular bronchiolitis; Lymphoid follicle; High resolution computed tomography