LEC 3 non-neoplastic bone diseases

• Osteoporosis:

  • Risk factors:
  • Age: Incidence increases with age due to reduced bone cell activity and attenuated cellular response to growth factors
  • Genetic factors: Runs in families, single gene defects (e.g., LRP5) and polymorphisms in other genes affect peak bone density
  • Hormones: Estrogen deficiencies accelerate osteoporosis
  • Nutritional status: Calcium and vitamin D deficiencies promote osteoporosis
  • Physical activity: Reduced activity promotes osteoporosis as mechanical forces stimulate bone remodeling
  • Aetiology:
• • Primary causes: Postmenopausal and senile osteoporosis due to age-related changes in bone density and structure
  • Secondary causes: Endocrine deficiencies, hyperfunction, gastrointestinal issues, bone marrow malignancies, drug use, lifestyle factors
  • Pathogenesis:
  • Hormonal influences: Estrogen deficiency major role, genetic factors, aging, physical activity
  • Morphology:
  • Thinning of trabecular and cortical bone, perforated trabecular plates, vertebral collapse, decreased bone quantity
  • Clinical manifestations/complications:
  • Thoracic and lumbar vertebral fractures common
• • Kyphoscoliosis, pulmonary embolism, pneumonia complications
• Osteomalacia:

  • Aetiology:
  • Inadequate mineralization of osteoid due to vitamin D deficiency or abnormal metabolism
  • Pathogenesis:
  • Inadequate mineralization of osteoid, weak and vulnerable bones prone to fractures
  • Morphology:
  • Excess osteoid, weak bones prone to fractures
  • Clinical manifestations/complications:
  • Weak bones, pain, bowing of legs, osteopenia, elevated alkaline phosphatase
• Rickets:

  • Aetiology:
  • Bone formed by growth plate does not mineralize due to vitamin D deficiency
  • Pathogenesis:
  • Bone formed by growth plate does not mineralize, affects children
  • Morphology:
  • Absence of cartilage palisade, poorly mineralized bone, bowing of legs
  • Clinical manifestations/complications:
  • Weak bones, fractures, bowing of legs, thoracic and lumbar vertebral fractures
• Paget Bone Disease:

  • Aetiology:
  • Genetic and environmental causes, mutations in SQSTM1 gene
  • Pathogenesis:
  • Mutations in SQSTM1 gene increase NF-KB activity, affecting osteoclast activity
  • Morphology:
  • Structurally disorganized bone, abnormal remodeling, increased vascularity, osteolytic, mixed, and osteosclerotic phases
  • Clinical manifestations/complications:
  • Bone pain, deformities, fractures, enlarged bones, arthritis, neurological complications