Honeycombing

Honeycombing results from the deposition of dense collagen fibers that destroy the characteristic alveolar structure,⁵ and is typically representative of end-stage lung disease.⁷ On HRCT, honeycomb cysts appear as enlarged airspaces that are often irregular in size, share thick walls, and are stacked upon one another. The cysts are typically 3-10 mm in diameter but can be as large as 2.5 cm.⁵⁷ When associated with a pattern of usual interstitial pneumonia typical of idiopathic pulmonary fibrosis, honeycombing typically has a peripheral, basal, and subpleural distribution.⁴⁵ The percentage of patients with IPF with honeycombing on HRCT varies in the literature, but it is estimated to be observed in one-third to two-thirds of patients.⁸⁹