6 Patterns > Fibrosis Pattern > Additional Features > w/ Honeycomb Only

Fibrosis w/ Honeycomb Only

Honeycomb is end-stage pulmonary fibrosis and may be seen in ANY advanced fibrosing intersitial lung disease.  It is similar to describing a liver biopsy as cirrhosis.  This tells your clinician that there is end-stage fibrosis, but does not tell them anything about the etiology of the fibrosis.

There are 4 histologic features of microscopic honeycomb remodeling:

  • Advanced scarring
  • Dilated cystic spaces embedded in the scar
  • Lined by ciliated epitheluim
  • Filled with mucinous material
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Advnaced scarring

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Dilated cystic spaces in scar

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Cysts filled with mucinous material

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Cysts lined by respiratory epithelium 

Knowledge of the CT imaging studies is essential in the setting of honeycomb only.

Diffuse Disease on CT

With diffuse disease on CT, and a biopsy with honeycomb, you can be confident in a diagnosis of chronic ILD.  CT distribution can help point to an etiology, as can the following features: 

  • Honeycomb without any other features > UIP of IPF
  • Giant cells and granulomas > Chronic HP and sarcoid
  • Marked Lymphoid hyperplasia (you may allow some degree of lymphoid hyperplasia in any advanced fibrosing process) and pleuritis > CTD
  • Abundant elastosis > PPFE 

Localized Disease on CT

If localized on CT, this is NOT a chronic ILD and consider the following:

  • Middle lobe syndrome
  • Recurrent infection
  • Aspiration
  • IgG4 disease
  • Congenital anomaly 

Sample Signout

If no imaging studies are available, consider the following approach to signing the case out:

End-stage lung with microscopic honeycomb remodeling (see comment).

Comment:  The biopsy consists of advanced fibrosis with microscopic honeycomb remodeling.  If the imaging studies show diffuse interstitial lung disease, this likely represents an advanced fibrotic ILD.  The 2011 ATS/ERS classification system suggests assigning this biopsy as a "Probable" UIP-pattern.  Many different ILDs could be responsible for the end-stage fibrosis seen in this case.

If the CT shows a localized lesion, this could be related to middle lobe syndrome, recurrent infection, aspiration, IgG4 disease, or a congenital anomaly.  Correlation with imaging studies and clinical history is suggested.