From "traction bronchiectasis" to honeycombing in idiopathic pulmonary fibrosis: A spectrum of bronchiolar remodeling also in radiology?

Abstract

Background: The diagnostic and prognostic impact of traction bronchiectasis on high resolution CT scan (HRCT) in patients suspected to have idiopathic pulmonary fibrosis (IPF) is increasing significantly.

Main body: Recent data demonstrated that cysts in honeycombing areas are covered by epithelium expressing bronchiolar markers. In IPF bronchiolization is the final consequence of a variety of pathogenic events starting from alveolar stem cell exhaustion, and ending in a abnormal/dysplastic proliferation of bronchiolar epithelium. CT scan features of traction bronchiectasis and honeycombing should be interpreted under the light of these new pathogenetic and morphologic considerations.

Short conclusion: We suggest that in IPF subjects traction bronchiectasis and honeycombing -now defined as distinct entities on HRCT scan- are actually diverse aspects of a continuous spectrum of lung remodeling.

Keywords: Bronchiolar dysplastic proliferation; Fibroblastic Foci; Honeycombing; Traction bronchiectasis.

Fig. 1

CT scan of a 52 years old lady, affected by idiopathic NSIP. Bilateral, peribronchovascular ground glass attenuation, due to intralobular fibrotic changes. Traction bronchiectasis are present bilaterally surrounded by ground glass,“fibrotic” attenuation, mainly in the right middle lobe and in both lower lobes. No honeycombing is present. A relative subpleural sparing is also visible

Fig. 2

Serial CT images of a 63 years old male affected by IPF. UIP pattern has been diagnosed through surgical lung biopsy at diagnosis. CT shows the progressive worsening of the coarseness. In 2007 (a, b) a moderate peripheral fibrotic reticulation is present. In the following years it progressively gets worse, particularly in the right lower lobe, with increase of the extension of traction bronchiectasis in 2010 (c, d) and with honeycombing and traction bronchiectasis in 2014 (e, f)