Honeycomb lung

What it means

Honeycombing represents destroyed and fibrotic lung tissue containing numerous cystic airspaces with thick fibrous walls, representing the late stage of various lung diseases, with complete loss of acinar architecture. The cysts range in size from a few millimeters to several centimeters in diameter, have variable wall thickness, and are lined by metaplastic bronchiolar epithelium. On chest radiographs, honeycombing appears as closely approximated ring shadows, typically 3-10 mm in diameter with walls 1-3 mm in thickness, that resemble a honeycomb; the finding implies end-stage lung disease. On CT scans, the appearance is of clustered cystic air spaces, typically of comparable diameters on the order of 3-10 mm but occasionally as large as 2.5 cm. Honeycombing is usually subpleural and is characterized by well-defined walls. It is a CT feature of established pulmonary fibrosis. Because honeycombing is often considered specific for pulmonary fibrosis and is an important criterion in the diagnosis of usual interstitial pneumonia, the term should be used with care, as it may directly impact patient care.

Pathologically, honeycombing is manifested as small air-containing cystic spaces that are lined by bronchiolar epithelium and have thickened walls of dense fibrous tissue. On high-resolution CT, honeycombing presents with a characteristic cystic appearance. The cystic spaces range from 3 mm to 1 cm in diameter, although they can be larger. The cystic spaces are characterized by well delineated walls 1 to 3 mm in thickness. The cysts are air-filled and appear lucent in comparison to normal lung parenchyma. Honeycombing is a manifestation of end-stage lung fibrosis.

Rare diseases that can present with this2

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category

Also called: Honeycomb cysts · Honeycombing