Clinical and Radiological Phenotypes and Endotypes

Abstract

Bronchiectasis is a heterogenous disease with multiple etiologies and associated comorbidities. As bronchiectasis is a complex disease, it is unsound to think of it as a single disease particularly when the differing etiologies are likely to be driving bronchiectasis through initial divergent molecular pathways, known as endotypes, that phenotypically present as the same disease due to protracted airway inflammation, but revealing potential differing underlying mechanisms that may have disparity of drug responses. Improved understanding of the cellular immune, inflammatory, and microbiological milieu associated with clinical and radiological features of bronchiectasis has resulted in the recognition of important endotypes and phenotypes that will allow for personalized treatments to improve quality of life and outcomes of patients with bronchiectasis. Here we discuss clinical and radiological phenotypes, as well as emerging molecular endotypes that are possible treatable traits in bronchiectasis.

Fig. 1

Bronchiectasis phenotypes/endotypes. CFTR, cystic fibrosis transmembrane conductance regulator; COPD, chronic obstructive pulmonary disease; NTM, nontuberculous mycobacteria.

Fig. 2

Radiological phenotypes. ( A ) Cylindrical bronchiectasis with signet ring sign. ( B ) Varicose bronchiectasis. ( C ) Cystic bronchiectasis. ( D ) Cavity in the right upper lobe. ( E ) Chronic pulmonary aspergillosis with right upper lobe cavitation with intracavitary material. ( F ) Tree-in-bud appearance. ( G ) Bronchocele in the left upper lobe in allergic bronchopulmonary aspergillosis. ( H ) Bilateral upper lobe bronchiectasis. ( I ) Isolated right middle lobe bronchiectasis. ( J ) Bronchiectasis in an area of hyperlucent lung with reduced vascularity (Swyer–James syndrome). ( K ) Situs inversus and bronchiectasis. ( L ) Mucus impaction of bronchiectatic airways.