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Differential Diagnosis of Musculoskeletal Disorders

Diffuse Osteosclerosis!!navigator!!

mnemonic: 5 M'S To PROoF

  • Metastases
  • Myelofibrosis
  • Mastocytosis
  • Melorheostosis
  • Metabolic: hypervitaminosis D, fluorosis, hypothyroidism, phosphorus poisoning
  • Sickle cell disease
  • Tuberous sclerosis
  • Pyknodysostosis, Paget disease
  • Renal osteodystrophy
  • Osteopetrosis
  • Fluorosis

Acquired Syndromes with Increased Bone Density!!navigator!!

  1. Renal osteodystrophy
  2. Osteoblastic metastases
  3. Paget disease of bone
  4. Erdheim-Chester disease
  5. Myelofibrosis
  6. Sickle cell disease

Constitutional Sclerosing Bone Disease!!navigator!!

  1. Progressive diaphyseal dysplasia
  2. Infantile cortical hyperostosis
  3. Melorheostosis
  4. Osteopathia striata
  5. Osteopetrosis
  6. Osteopoikilosis
  7. Pachydermoperiostosis
  8. Pyknodysostosis
  9. Van Buchem disease
  10. Williams syndrome

Sclerosing Bone Dysplasia!!navigator!!

Endochondral bone formation:

  • primary spongiosa forms at 7th week of embryogenesis → resorption around 9th week with conversion into secondary spongiosa→ osteoclastic remodeling into trabeculae + medullary cavity

Target sites for endochondral bone formation:

  • tubular + flat bones, vertebrae, skull base, ethmoids, ends of clavicle

Intramembranous ossification:

  • = transformation of mesenchymal cells into cortical bone without intervening cartilaginous matrix beginning at 9th week of fetal life to beyond closure of growth plates

Target sites for intramembranous bone formation:

  • cortex of tubular + flat bones, calvaria, upper facial bones, tympanic temporal bone, vomer, medial pterygoid process
  1. DYSPLASIA OF ENDOCHONDRAL OSSIFICATION (PRIMARY SPONGIOSA)
    • = failure in resorption + remodeling of primary immature spongiosa by osteoclasts
    • accumulation of calcified cartilage matrix packing the medullary cavity
    1. Osteopetrosis
    2. Pyknodysostosis
  2. DYSPLASIA OF ENDOCHONDRAL OSSIFICATION (SECONDARY SPONGIOSA)
    = errors in resorption + remodeling of secondary spongiosa
    • focal densities / striations along trabecular bone
    1. Osteopoikilosis
    2. Osteopathia striata
  3. DYSPLASIA OF INTRAMEMBRANOUS OSSIFICATION
    • = disequilibrium between periosteal bone formation + endosteal bone resorption
    1. Progressive diaphyseal dysplasia
    2. Hereditary multiple diaphyseal sclerosis
    3. Hyperostosis corticalis generalisata
    4. Diaphyseal dysplasia with anemia
    5. Oculodento-osseous dysplasia
    6. Trichodento-osseous dysplasia
    7. Kenny-Caffey syndrome
  4. MIXED SCLEROSING DYSPLASIAS = OVERLAP SYNDROME
    1. predominantly endochondral disturbance
      1. Dysosteosclerosis
      2. Metaphyseal dysplasia (Pyle disease)
      3. Craniometaphyseal dysplasia
      4. Frontometaphyseal dysplasia
    2. predominantly intramembranous defects
      1. Melorheostosis
      2. Craniodiaphyseal dysplasia
      3. Lenz-Majewski hyperostotic dwarfism
      4. Progressive diaphyseal dysplasia

Nonhereditary Sclerosing Dysplasia!!navigator!!

  1. Intramedullary osteosclerosis
  2. Melorheostosis
  3. Overlap syndromes
    = disorder of endochondral + intramembranous ossification
    Combination: melorheostosis + osteopoikilosis + osteopathia striata

Solitary Osteosclerotic Lesion!!navigator!!

  1. DEVELOPMENTAL
    1. Bone island
  2. VASCULAR
    1. Old bone infarct
    2. Aseptic / ischemic / avascular necrosis
  3. HEALING BONE LESION
    1. trauma: callus formation in stress fracture
    2. benign tumor: fibrous cortical defect / nonossifying fibroma; brown tumor; bone cyst
    3. malignant tumor: lytic metastasis after radiation, chemotherapy, hormone therapy
  4. INFECTION / INFLAMMATION
    (low-grade chronic infection / healing infection)
    1. Osteoid osteoma
    2. Chronic / healed osteomyelitis: bacterial, tuberculous, fungal
    3. Sclerosing osteomyelitis of Garré
    4. Granuloma
    5. Brodie abscess
  5. BENIGN TUMOR
    1. Osteoma
    2. Osteoblastoma
    3. Ossifying fibroma
    4. Healed fibrous cortical defect
    5. Enchondroma / osteochondroma
  6. MALIGNANT TUMOR
    1. Osteoblastic metastasis: prostate, breast
    2. Lymphoma
    3. Sarcoma: osteo-, chondro-, Ewing sarcoma
  7. OTHERS
    1. Sclerotic phase of Paget disease
    2. Fibrous dysplasia

Cortical Sclerotic Lesion in Child

  1. Osteoid osteoma
  2. Stress fracture
  3. Chronic osteomyelitis
  4. Healed fibrous cortical defect

Multiple Osteosclerotic Lesions!!navigator!!

  1. FAMILIAL
    1. Osteopoikilosis
    2. Enchondromatosis = Ollier disease
    3. Melorheostosis
    4. Multiple osteomas: associated with Gardner syndrome
    5. Osteopetrosis
    6. Pyknodysostosis
    7. Osteopathia striata
    8. Chondrodystrophia calcificans congenita
    9. Multiple epiphyseal dysplasia = Fairbank disease
  2. SYSTEMIC DISEASE
    1. Mastocytosis = urticaria pigmentosa
    2. Tuberous sclerosis

Bone-within-bone Appearance!!navigator!!

= endosteal new bone formation

  1. Normal
    1. thoracic + lumbar vertebrae (in infants)
    2. growth recovery lines (after infancy)
  2. Infantile cortical hyperostosis (Caffey)
  3. Sickle cell disease / thalassemia
  4. Congenital syphilis
  5. Osteopetrosis / oxalosis
  6. Radiation
  7. Acromegaly
  8. Paget disease
  9. Gaucher disease

mnemonic: BLT PLT RSD RSD

  • Bismuth ingestion
  • Lead ingestion
  • Thorium ingestion
  • Petrosis (osteopetrosis)
  • Leukemia
  • Tuberculosis
  • Rickets
  • Scurvy
  • D toxicity (vitamin D)
  • RSD (reflex sympathetic dystrophy)

Dense Metaphyseal Bands!!navigator!!

mnemonic: DENSE LINES

  • D-vitamin intoxication
  • Elemental arsenic + heavy metals: lead, bismuth, phosphorus
  • Normal variant
  • Systemic illness
  • Estrogen to mother during pregnancy
  • Leukemia
  • Infection (TORCH), Idiopathic hypercalcemia
  • Never forget healed rickets
  • Early hypothyroidism (cretinism)
  • Scurvy, congenital Syphilis, Sickle cell disease
  • also: methotrexate therapy

Outline