Primary Ciliary Dyskinesia (PCD) is a rare, inherited condition distinguished by abnormal function of motile cilia. In lung airways, motile cilia are essential for effective mucociliary transport, an important host defense to prevent infection of airways. People with PCD have chronic/recurrent respiratory infection and bronchiectasis is a common finding in adulthood.

In a recent case report published in the American Journal of Respiratory and Critical Care Medicine from David Meyerholz, DVM, PhD and Douglas Hornick, MD, a 41-year-old male was referred to the University of Iowa with bronchiectasis, chronic sinusitis, and peculiar airway calcifications. The patient self-reported a history of recurrent airway infections and productive cough but denied lithoptysis. Chest computed tomography and bronchoscopy confirmed bronchiectasis and broncholiths. Sputum grew Pseudomonas aeruginosa. Low nasal nitric oxide and homozygous CCDC40 mutations confirmed a diagnosis of PCD. Over time, lung function declined requiring bilateral lung transplant. 

Pathological examination of PCD airways found luminal broncholiths of varying sizes often associated with inflammation. Several broncholiths were adherent to the airway wall. Microscopically, adherent broncholiths were often composed of concentric lamellar mineralization with tethers attached to the airway wall. In some cases, the submucosal glands were dilated and filled with similar mineralized concretions.

This study raised several pointed questions that can guide future research:

1. Could impaired airway clearance alone or in combination with chronic inflammation explain why PCD lungs are at increased risk for broncholithiasis?
2. Why do people with PCD >40 years of age have elevated susceptibility to broncholithiasis compared to younger ages?
3. Does the presence of mineralized concretions near and within submucosal glands suggest a role for altered secretions in broncholithiasis pathogenesis?