Bronchiolitis and Bronchiolar Disorders

Abstract

Bronchioles are noncartilaginous small airways with internal diameter of 2 mm or less, located from approximately the eighth generation of purely air conducting airways (membranous bronchioles) down to the terminal bronchioles (the smallest airways without alveoli) and respiratory bronchioles (which communicate directly with alveolar ducts and are in the range of 0.5 mm or less in diameter). Bronchiolar injury, inflammation, and fibrosis may occur in myriad disorders including connective tissue diseases, inflammatory bowel diseases, lung transplant allograft rejection, graft versus host disease in allogeneic stem cell recipients, neuroendocrine cell hyperplasia, infections, drug toxicity (e.g., penicillamine, busulfan), inhalation injury (e.g., cigarette smoke, nylon flock, mineral dusts, hard metals, Sauropus androgynous); idiopathic, common variable immunodeficiency disorder, and a host of other disorders or insults. The spectrum of bronchiolar disorders is wide, ranging from asymptomatic to fatal obliterative bronchiolitis. In this review, we discuss the salient clinical, radiographic, and histological features of these diverse bronchiolar disorders, and discuss a management approach.

A breath of not so fresh air…

“…Its inhalation can result in acute, permanent and/or even life-threatening injury. Some cases of chronic exposure resulting in bronchiolitis obliterans have also been reported [5,[14][15][16]. NO 2 toxicity has also been described in other settings such as in poorly ventilated combustion areas or indoor ice rinks [17].…”

Environmental and occupational bronchiolitis obliterans: new reality

“… 27 PrB is now most commonly categorized under the umbrella of OP or cryptogenic OP (COP) because it was realized that fibrotic material within the airway lumen most often extends from the alveolar compartment. 28 , 29 …”

“…ConB can be identified on lung biopsy as a distinct pathology or combined with other small airways and lung parenchymal pathologies. 28 , 51 , 52 , 53 The most frequent findings associated with ConB are cellular bronchiolitis, respiratory bronchiolitis, and bronchiolar metaplasia.…”

Influence of SARS-CoV-2 on airway mucus production: A review and proposed model

“…Mouse trachea Caliber (mm) 74,80,85 15-20 0.5-1.0 *1.5 Submucosal glands (mL cm �2 ) 14,70 [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] Zero Zero to rare Surface epithelium height (mm) 87,94…”