A 24-year-old man has had recurrent sinopulmonary infections since childhood. Examination shows dextrocardia and situs inversus. High resolution CT shows cylindrical bronchiectasis of the lower lobes. Electron microscopy of nasal mucosal cilia would most likely show:

• A Accumulation of viscous mucus plugging the airway lumen
• B Thickened basal lamina beneath the ciliated epithelium
• C Defective alpha-1 antitrypsin folding in the endoplasmic reticulum
• D Absence of the outer dynein arms ✓

Explanation

This is Kartagener syndrome, a subtype of primary ciliary dyskinesia defined by situs inversus, sinusitis, and bronchiectasis. The defect lies in ciliary ultrastructure, classically absent or shortened outer (and inner) dynein arms, producing immotile cilia. Defective alpha-1 antitrypsin folding causes panacinar emphysema and liver disease, not bronchiectasis. Thickened basement membrane is a feature of asthma, and luminal mucus plugging describes cystic fibrosis, where the structural ciliary apparatus is normal.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.