= ENGELMANN-CAMURATI DISEASE = CAMURATI-ENGELMANN DISEASE

= autosomal dominant disorder of intramembranous ossification

Genetics: mutation in gene encoding transforming growth factor TGF-β1 (= latency-associated peptide causing premature activation of TGF-β1) on chromosome 19q13.1 → hyperostosis along periosteal + endosteal surfaces

Age: 5–25 years (primarily in childhood); M >F

• neuromuscular dystrophy = delayed walking (18–24 months) with broad-based waddling gait; often misdiagnosed as muscular dystrophy / poliomyelitis
• bone pain + tenderness usually in midshaft of long bones
• muscle pain + weakness with easy fatigability in legs:
  • underdevelopment of muscles ← malnutrition
• NORMAL laboratory values

Location: usually symmetric involvement of diaphyses of long bones, calvaria, mandible, facial bones, midsegment of clavicle; NO involvement of hands, feet, ribs, scapulae

• Skull (initially affected)
  • amorphous sclerosis of skull base → cranial nerve palsy
  • encroachment of frontal + sphenoid sinus; sparing of maxillary sinus
  • mandible rarely affected
• Long bones
  Site: tibia >femur >fibula >humerus >ulna >radius
  • bilateral symmetric cortical thickening involving periosteal + endosteal surfaces of long bones:
    • fusiform enlargement of diaphysis
    • abrupt demarcation of lesions ← sparing of metaphyses + epiphyses ← formed by endochondral ossification
    • cortical thickening ( = endosteal + periosteal accretion of mottled new bone) → progressive obliteration of medullary cavity
  • progression of lesions along long axis of bone toward either end
  • relative elongation of extremities

Rx: low-dose corticosteroids

DDx:

1. Chronic osteomyelitis (single bone)
2. Hyperphosphatasemia (high alkaline phosphatase levels)
3. Paget disease (age, new-bone formation, increased alkaline phosphatase)
4. Infantile cortical hyperostosis (fever; mandible, rib, clavicles; regresses, <1 year of age)
5. Fibrous dysplasia (predominantly unilateral, subperiosteal new bone)
6. Osteopetrosis (very little bony enlargement)
7. Vitamin A poisoning