Bronchiolitis obliterans (BO) is a rare, chronic form of obstructive lung disease, often initiated with injury of the bronchiolar epithelium followed by an inflammatory response and progressive fibrosis of small airways resulting in nonuniform luminal obliteration or narrowing. The term BO comprises a group of diseases with different underlying etiologies, courses, and characteristics. Among the better recognized inciting stimuli leading to BO are airway pathogens such as adenovirus and mycoplasma, which, in a small percentage of infected children, will result in progressive fixed airflow obstruction, an entity referred to as postinfectious bronchiolitis obliterans (PIBO). The present knowledge on BO in general is reasonably well developed, in part because of the relatively high incidence in patients who have undergone lung transplantation or bone marrow transplant recipients who have had graft-versus-host disease in the posttransplant period. The cellular and molecular pathways involved in PIBO, while assumed to be similar, have not been adequately elucidated. Since 2016, an international consortium of experts with an interest in PIBO assembles on a regular basis in Geisenheim, Germany, to discuss key areas in PIBO which include diagnostic workup, treatment strategies, and research fields.
Several studies have investigated the association of a promoter polymorphism in CD14 with atopic phenotypes. We screened this and another polymorphism in 182 asthmatic children and found no association with asthma. Furthermore, there was substantial linkage disequilibrium of the polymorphisms. Thus CD14 does not play a major role in the development of asthma in our population of Caucasian children.
Rationale
Bronchiolitis obliterans syndrome (BOS) is a severe, chronic inflammation of the airways leading to an obstruction of the bronchioles. So far, there are only a few studies looking at the long‐term development of pulmonary impairment in children with BOS.
Objective
The objective of this study was to investigate the incidence and long‐term outcome of BOS in children who underwent allogeneic hematopoietic stem cell transplantation (HSCT).
Methods
Medical charts of 526 children undergoing HSCT in Frankfurt/Main, Germany between 2000 and 2017 were analyzed retrospectively and as a result, 14 patients with BOS were identified. A total of 271 lung functions (spirometry and body plethysmography), 26 lung clearance indices (LCI), and 46 chest high‐resolution computed tomography (HRCT) of these 14 patients with BOS were evaluated.
Results
Fourteen patients suffered from BOS after HSCT (2.7%), whereby three distinctive patterns of lung function impairment were observed: three out of 14 patients showed a progressive lung function decline; two died and one received a lung transplant. In five out of 14 patients with BOS persisted with a severe obstructive and secondarily restrictive pattern in lung function (forced vital capacity [FVC] < 60%, forced expiratory volume in 1 second [FEV1] < 50%, and FEV1/FVC < 0.7) and increased LCI (11.67‐20.9), six out of 14 patients recovered completely after moderate lung function impairment and signs of BOS on HRCT. Long‐term FVC in absolute numbers was increased indicating that the children still have lung growth.
Conclusion
Our results showed that the incidence of BOS in children is low. BOS was associated with high mortality and may lead to persistent obstructive lung disease; although, lung growth continued to exist.
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