This case nicely illustrates the overlapping appearances of subacute hypersensitivity pneumonitis and respiratory bronchiolitis. Given the absence of a strong smoking history, hypersensitivity pneumonitis is favored in this case. However, both can be characterized by centrilobular micronodules, groundglass opacities, and mosaic attenuation/air trapping. Respiratory bronchiolitis tends to have a stronger apical predominance, with hypersensitivity pneumonitis more pronounced in the mid and lower lung fields.

In this case, both diagnoses belong in the differential, and the clinical workup, follow-up, and treatment can be determined with pulmonology care.