Exposure-related bronchiolitis is becoming more widely recognised as an essential but difficult clinical diagnosis. Acute and chronic inhalation exposures are linked to a variety of clinical manifestations as well as a range of histopathologic abnormalities affecting the small airways. This review covers the histologic patterns and occupational contexts for exposure-related bronchiolitis, as well as recent improvements in illness diagnosis and therapy. In exposure-related bronchiolitis, the full histopathologic spectrum of bronchiolitis (constrictive, obliterative, proliferative, lymphocytic, respiratory) has been observed. Recent research has found that lung clearance index testing and impulse oscillometry are more sensitive than spirometry in detecting small airway abnormalities and may help in the diagnosis of occupational bronchiolitis. The prognosis of indolent occupational bronchiolitis appears to be better than that of other forms of bronchiolitis, although it varies depending on the degree of bronchiolar inflammation and the stage of disease at which exposure is removed.

There is no pathognomonic histopathologic pattern of bronchiolitis for occupational bronchiolitis since one or more histologic patterns may be present. For exposure and illness identification, a high level of suspicion is required. Transbronchial cryobiopsy, lung clearance index testing, and impulse oscillometry are recent breakthroughs that may assist in diagnosis, although more study is needed.

Reference: https://journals.lww.com/co-allergy/Abstract/2018/04000/The_emerging_spectrum_of_exposure_related.5.aspx