Fig. 1.

Interstitial pneumonia with autoimmune features (IPAF) in a 67-year-old man.

(a, b) Lung window images of CT scans obtained at levels of right inferior pulmonary vein (a) and liver dome (b), respectively, show subpleural reticulation and traction bronchiolectasis (arrowheads) in both lungs. Patient had positive serologic tests; fluorescent antinuclear antibody (FANA, 1:320) and perinuclear antineutrophil cytoplasmic antibody (pANCA, 1:320). (c) Low-power magnification of lung demonstrates collapse of two secondary lobules (arrows) resulting in dilation of distal small airways (so-called honeycombing) with super imposed lymphoid follicles with reactive germinal centers (F). The histologic pattern is most consistent with UIP, the superimposed lymphoid follicles with reactive germinal centers suggest CTD as the underlying cause of all the histopathologic findings but are not specific. (d, e). Four-year follow-up CT scans obtained at similar levels to a & b, respectively, depict apparent areas of CT honeycombing (arrows) in posterior aspects of both lower lobes.