Primary ciliary dyskinesia — structured clinical encounter

Station brief (candidate)

You are the paediatric registrar in a respiratory clinic. A 4-year-old girl is referred with a wet cough that has been present on most days since she was a few weeks old. She had unexplained respiratory distress as a term newborn, has a constantly runny nose, and has had recurrent glue ear needing two sets of grommets. A chest radiograph shows the heart on the right. The team asks you to establish the diagnosis, exclude the key alternative, plan the diagnostic pathway, and outline long-term management. You have 12 minutes with the team and 5 minutes for examiner discussion. [4] [1]

Information available on request

• 4-year-old girl; daily wet productive cough since the first weeks of life; unexplained term neonatal respiratory distress requiring oxygen. [4]
• Chronic year-round rhinorrhoea and nasal congestion from the neonatal period; recurrent otitis media with effusion and two sets of grommets with intermittent discharge. [4]
• Examination: mild clubbing, coarse crackles at both bases, discharging left grommet, dextrocardia with the apex beat on the right and the liver edge on the left. [4]
• Growth: tracking along the 25th centile with no steatorrhoea. [2]
• Sweat chloride (on request): normal, making cystic fibrosis unlikely. [2]
• Nasal nitric oxide (on request): very low. [1]
• High-speed video microscopy and electron microscopy (on request): abnormal ciliary beat pattern with absent outer dynein arms. [1]

Tasks

1. Give the diagnosis and the features that support it, including the significance of the neonatal history and situs. [4]
2. State the key alternative diagnosis and how you exclude it. [2]
3. Outline the diagnostic pathway and why no single test suffices. [1]
4. Outline the cornerstone and the components of long-term management. [5]
5. State the role and evidence for maintenance azithromycin. [9]

Marking anchors

Must-hit

• Diagnoses primary ciliary dyskinesia (Kartagener syndrome given situs inversus) on the basis of a daily wet cough since infancy, unexplained term neonatal respiratory distress, chronic rhinorrhoea, recurrent otitis media with effusion, and dextrocardia; explains that neonatal distress in a term baby is an early clue and that situs inversus occurs in only about half of cases so normal situs would not exclude it. [4]
• Names cystic fibrosis as the key alternative and excludes it with a sweat chloride test and assessment of pancreatic function and growth. [2]
• Describes the specialist diagnostic pathway combining nasal nitric oxide, high-speed video microscopy, electron microscopy and genetics, and explains that no single test is sufficient. [1]

Merit

• States that daily airway clearance physiotherapy is the cornerstone of management, alongside surveillance cultures with prompt culture-directed antibiotics and Pseudomonas eradication, monitoring of lung function, ENT and audiology care, immunisation and smoke avoidance, and genetic counselling; and cites the BESTCILIA trial showing maintenance azithromycin reduces exacerbations. [5] [9]

Fail

• Reassures the family that dextrocardia is harmless and treats the chronic wet cough as asthma or recurrent viral illness without a structured search for a cause. [4]
• Fails to exclude cystic fibrosis before settling on the diagnosis. [2]