Follicular bronchiolitis (FB) is a nonneoplastic primary polyclonal B cell hyperplasia of the bronchus-associated lymphoid tissue (BALT) due to chronic exposure to antigens in those with underlying collagen vascular or immune deficiency diseases which usually manifested as small centrilobular ground glass nodules with lower lobe distribution.
It is defined as lymphoid hyperplasia of the BALT and histologically characterized by polyclonal B cell hyperplasia of the lymphoid follicles with reactive germinal centers principally distributed along bronchioles with only minimal infiltration of alveolar septae.
Many cases of follicular bronchiolitis are associated with various systemic illnesses which include
- collagen vascular diseases / connective tissue diseases 1-2
- immunodeficiency states both congenital and acquired:
A key feature described with follicular bronchiolitis on HRCT includes small ground glass centrilobular nodules of 3mm diameter in lower lobes that are variably associated with peribronchial nodules 1.
Other features (albeit non-specific) include:
Treatment and prognosis
Treatment should target the underlying condition as well as administration of steroid and immunosuppressants. The overall prognosis will depend on the underlying or associated abnormality. Some case may respond to macrolide antibiotics 6.
- 1. Howling SJ, Hansell DM, Wells AU et-al. Follicular bronchiolitis: thin-section CT and histologic findings. Radiology. 1999;212 (3): 637-42. Radiology (full text) - Pubmed citation
- 2. Pipavath SJ, Lynch DA, Cool C et-al. Radiologic and pathologic features of bronchiolitis. AJR Am J Roentgenol. 2005;185 (2): 354-63. AJR Am J Roentgenol (full text) - Pubmed citation
- 3. Boiselle PM, Lynch DA. CT of the Airways. Humana Press. (2009) ISBN:1607615509. Read it at Google Books - Find it at Amazon
- 4. Reittner P, Fotter R, Lindbichler F et-al. HRCT features in a 5-year-old child with follicular bronchiolitis. Pediatr Radiol. 1997;27 (11): 877-9. - Pubmed citation
- 5. Kinoshita M, Higashi T, Tanaka C et-al. Follicular bronchiolitis associated with rheumatoid arthritis. Intern. Med. 1992;31 (5): 674-7. Pubmed citation
- 6. Boiselle PM, Lynch D. CT of the Airways. Humana Press. (2008) ISBN:1588298485. Read it at Google Books - Find it at Amazon