TOACS FCPS Station · Chest X-ray in Cleidocranial Dysplasia

📷 Chest X-ray – Cleidocranial Dysplasia

Chest X-ray showing hypoplastic or absent clavicles and a widened thorax, characteristic of cleidocranial dysplasia

Figure 1 · Cleidocranial Dysplasia · RUNX2 mutation

🔍 Key radiographic features:

✓ Hypoplastic or absent clavicles – partial or complete absence
✓ Widened thorax – due to absent clavicular support
✓ Delayed ossification – of pubic symphysis, fontanelles
✓ Wormian bones – intrasutural bones (skull)
✓ Shoulders can be approximated – midline opposition possible

📋 Clinical scenario (examiner prompt)

A 1‑month‑old infant is referred for evaluation of unusual shoulder mobility. On examination, the anterior fontanelle is wide open. . A chest X‑ray (see image) shows absence of both clavicles and a widened thorax. .

Absent clavicles on chest X-ray Widened thorax wide Open fontanelle. Shoulders can meet midline

🧑‍⚕️ Examiner tasks · TOACS

1. Identify the diagnosis from the clinical image and context.

2. Describe the radiographic findings (hypoplastic/absent clavicles, widened thorax).

3. Explain the underlying condition (cleidocranial dysplasia, RUNX2 mutation).

4. Discuss management (dental, orthopedic, genetic counseling).

⚠️ Key concept: Cleidocranial dysplasia (CCD) is an autosomal dominant disorder caused by RUNX2 mutations. The hallmark feature is hypoplastic or absent clavicles, allowing the shoulders to be approximated midline. Other features include patent fontanelles (may remain open into adulthood), supernumerary teeth (hyperdontia), wormian bones, short stature, and widened thorax on chest X‑ray. Management involves dental extraction of supernumerary teeth and orthodontic treatment, monitoring for hearing loss (otitis media), and genetic counseling.

🎯 Expected answers (for examiners)

• Diagnosis: Cleidocranial dysplasia (RUNX2)
• Radiographic findings: Hypoplastic or completely absent clavicles (unilateral or bilateral); widened thorax; delayed closure of sutures/fontanelles; wormian bones (skull); delayed ossification of pubic symphysis; short stature
• Clinical features: Open anterior fontanelle (may persist into adulthood); supernumerary teeth (hyperdontia); delayed eruption of permanent teeth; ability to bring shoulders together in front of chest; short stature; mild intellectual disability (in some); recurrent otitis media; hearing loss
• Genetics: RUNX2 gene (chromosome 6p21); autosomal dominant; transcription factor essential for osteoblast differentiation
• Management: Dental: extraction of supernumerary teeth, orthodontic treatment, dental prostheses; ENT: hearing screening (otitis media); orthopedic: treat fractures, monitor for scoliosis; genetic counseling (autosomal dominant, 50% recurrence risk)

📌 Cleidocranial dysplasia – key points:
• Gene: RUNX2 (transcription factor)
• Clavicles: Hypoplastic/absent → shoulders meet midline
• Skull: Patent fontanelles, wormian bones, delayed suture closure
• Teeth: Supernumerary teeth (hyperdontia), delayed eruption
• Inheritance: Autosomal dominant
• Management: Dental extraction, orthodontics, ENT monitoring

⚡ Quick FCPS‑style MCQ

A child with open fontanelles, supernumerary teeth, and a chest X-ray showing absent clavicles. The most likely diagnosis is:

A. Campomelic dysplasia B. Cleidocranial dysplasia C. Nail-patella syndrome D. Leri-Weill dyschondrosteosis

📌 Topic summary · Chest X-ray in Cleidocranial Dysplasia

Condition
Cleidocranial dysplasia (CCD)

Gene
RUNX2 (autosomal dominant)

Chest X-ray
Hypoplastic/absent clavicles

Other features
Open fontanelles, supernumerary teeth

Management
Dental extraction, orthodontics, ENT

Prognosis
Normal intelligence (usually)

Feature	Cleidocranial Dysplasia
Gene	RUNX2 (runt-related transcription factor 2) – 6p21
Inheritance	Autosomal dominant (most de novo)
Chest X-ray findings	Hypoplastic or absent clavicles (unilateral or bilateral); widened thorax; delayed ossification
Skull findings	Patent anterior fontanelle (may persist into adulthood); wormian bones; delayed suture closure; brachycephaly
Dental findings	Supernumerary teeth (hyperdontia), delayed eruption of permanent teeth, retained primary teeth
Other features	Short stature (proportionate); shoulders can be opposed midline; recurrent otitis media; hearing loss; mild intellectual disability (rare); pubic symphysis diastasis
Management – Dental	Extraction of supernumerary teeth, orthodontic treatment, dental prostheses
Management – ENT	Hearing screening (otitis media), consider tympanostomy tubes
Management – Other	Genetic counseling (50% recurrence risk); monitor for scoliosis; treat fractures

🩻 TOACS FCPS Station · Chest X-ray in Cleidocranial Dysplasia

📷 Chest X-ray – Cleidocranial Dysplasia

🧑‍⚕️ Examiner tasks · TOACS

📌 Topic summary · Chest X-ray in Cleidocranial Dysplasia