"Bubbly lung", a honeycombing variant with more favorable outcome.

Background: Although radiologic honeycombing is generally associated with progressive fibrosis and a dismal prognosis, some patients display an unexpectedly indolent clinical course. We aimed to assess for variants of honeycombing associated with a more favorable prognosis.

Methods: A computer-assisted search was conducted to identify patients encountered at Mayo Clinic from 1998 to 2022 who had undergone chest CT that manifested exuberant honeycombing. Medical records and chest imaging studies were reviewed to identify clinical, pulmonary function and radiologic features.

Results: Among 136 patients with exuberant honeycombing, 23 patients were identified with CT features of what we termed "bubbly lung" characterized by extensive macrocystic fibrosis; 17 (74%) were female with a median age of 71 years (range, 32-88) at baseline. Underlying diagnoses were ANCA associated vasculitis (22%), overlap CTD (22%), rheumatoid arthritis (17%), IPF (17%), IPAF (9%), systemic sclerosis (4%), undifferentiated CTD (4%), and dermatomyositis (4%). Median FVC was 78% predicted (range 35-112), median DLco was 41% predicted (range 10-92), and median TLC was 73% predicted (range 57-116). Serial FVC measurements were available for 19 (83%) patients with a median interval of 4.7 years (range: 0.4-20); median FVC change per year was 23 ml (range -279 to +232) and median FVC % predicted change per year was 0.00% (range -3.20 to +6.79%). The median survival was 7.1 years, 5-year survival was 76% (95% CI: 58%-100%) and 10-year survival was 48%.

Conclusions: "Bubbly lung" is a variant of exuberant honeycombing that is associated with better-than-expected outcome and FVC decline per year.