TOACS FCPS Station · X‑ray Hands: Mucopolysaccharidoses

📷 X‑ray Hands (AP view)

Hand X-ray showing proximally pointed and tapering (bullet-like) metacarpals in MPS

Figure 1 · AP hand radiograph · Mucopolysaccharidosis – Bullet‑Shaped Metacarpals

🔍 Key radiographic features:

✓ Proximally pointed and tapering (bullet‑shaped) metacarpals
✓ Irregular, shortened metacarpal bones – proximal ends are pointed
✓ Wide phalanges with constricted diaphyses (“oar‑shaped” appearance)
✓ Delayed carpal bone ossification – few carpal bones for age
✓ Dysostosis multiplex – generalized skeletal dysplasia pattern

📋 Clinical scenario (examiner prompt)

A 3‑year‑old child presents with coarse facial features, hepatosplenomegaly, and joint stiffness. The child has corneal clouding and developmental delay. A hand X‑ray (AP view) is shown.

Coarse facies Bullet‑shaped metacarpals Corneal clouding Hepatosplenomegaly

🧑‍⚕️ Examiner tasks · TOACS

1. Identify the diagnosis from the hand X‑ray and clinical context.

2. Describe the X‑ray findings (bullet‑shaped metacarpals, dysostosis multiplex).

3. Explain the pathophysiology (lysosomal storage of GAGs, skeletal dysplasia).

4. Discuss differential diagnosis and management (MPS types, ERT, HSCT).

⚠️ Key concept: Proximally pointed and tapering (bullet‑shaped) metacarpals are a classic skeletal finding in mucopolysaccharidoses (MPS), particularly MPS I (Hurler), MPS II (Hunter), and MPS VI (Maroteaux‑Lamy). This finding is part of dysostosis multiplex, a characteristic skeletal dysplasia pattern in MPS.

🎯 Expected answers (for examiners)

• Diagnosis: Mucopolysaccharidosis (likely MPS I-H, Hurler syndrome)
• X‑ray findings: Proximally pointed/tapering metacarpals (bullet‑shaped), irregular metaphyses, delayed carpal ossification
• Pathophysiology: Deficiency of lysosomal enzyme → accumulation of GAGs → skeletal dysplasia (dysostosis multiplex)
• Management: Enzyme assay (α‑L‑iduronidase), urine GAGs, ERT (laronidase), HSCT for MPS I-H

⚡ Quick FCPS‑style MCQ

Bullet‑shaped metacarpals on hand X‑ray in a child with coarse facies and hepatosplenomegaly are most consistent with:

A. Mucopolysaccharidosis (MPS) B. Mucolipidosis C. Osteogenesis imperfecta D. Achondroplasia

📌 Topic summary ·

Bullet‑shaped metacarpals
MPS I, II, VI

Dysostosis multiplex
Generalized skeletal dysplasia

Corneal clouding
Absent in MPS II (Hunter)

X‑linked
MPS II (Hunter)

Normal intelligence
MPS IV, VI

Treatment
ERT, HSCT (MPS I)

MPS Type	Key Skeletal Feature
MPS I (Hurler)	Bullet‑shaped metacarpals, dysostosis multiplex
MPS II (Hunter)	Bullet‑shaped metacarpals, clear corneas
MPS IV (Morquio)	Odontoid hypoplasia, platyspondyly
MPS VI (Maroteaux‑Lamy)	Bullet‑shaped metacarpals, normal intelligence

🩻 TOACS FCPS Station · X‑ray Hands: Mucopolysaccharidoses (MPS)

📷 X‑ray Hands (AP view)

🧑‍⚕️ Examiner tasks · TOACS

📌 Topic summary ·