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Information

Differential Diagnosis of Skull and Spine Disorders

Pediatric Presacral Mass!!navigator!!

  1. Congenital & developmental mass
    1. Sacrococcygeal teratoma
    2. Anterior sacral meningocele
    3. Dermoid cyst
    4. Enteric cyst
    5. Cystic lymphatic malformation
  2. Neurogenic mass
    1. Neuroblastoma
    2. Ganglioneuroma
    3. Schwannoma
    4. Neurofibroma
  3. Mesenchymal mass
    1. Rhabdomyosarcoma
    2. Undifferentiated sarcoma
    3. Lymphoma
    4. Vascular malformation
  4. Sacral mass with presacral extension
    1. benign primary sacral tumor
      1. Giant cell tumor
      2. Aneurysmal bone cyst
    2. malignant primary sacral tumor
      1. Chordoma
      2. Ewing sarcoma
  5. Inflammatory mass
    1. Pelvic abscess
    2. Pelvic hematoma

Sacroiliitis!!navigator!!

  • findings predominate on the iliac side (thinner cartilage)
  1. BILATERAL SYMMETRIC
    1. Ankylosing spondylitis
      • small regular erosion = loss of definition of white cortical line on iliac side (initially)
      • subchondral sclerosis + subsequent ankylosis
      • ossification of interosseous ligaments
    2. Enteropathic arthropathy
      • same signs as in ankylosing spondylitis
    3. Rheumatoid arthritis (in late stages)
      • joint space narrowing without reparation
      • osteoporosis
      • ankylosis may occur
    4. Deposition arthropathy: gout, CPPD, ochronosis, acromegaly
      • slow loss of cartilage
      • subchondral reparative bone + osteophytes
    5. Osteitis condensans ilii
      DDx: Hyperparathyroidism (subchondral bone resorption on iliac side resembling erosion + widening of joint)
  2. BILATERAL ASYMMETRIC
    1. Psoriatic arthritis
      • large extensive erosion
      • subchondral sclerosis + occasional ankylosis
    2. Reiter syndrome
    3. Juvenile rheumatoid arthritis
  3. UNILATERAL
    1. Infection
    2. Osteoarthritis from abnormal mechanical stress
      • no erosions
      • irregular narrowing of joint space with subchondral sclerosis
      • osteophytes at anterosuperior / -inferior aspect of joint (may resemble ankylosis)

DDx: psoriatic arthritis, Reiter syndrome, trauma, gout, pigmented villonodular synovitis, osteitis condensans ilii

Sacroiliac Joint Widening!!navigator!!

mnemonic: CRAP TRAP

  • Colitis
  • Rheumatoid arthritis
  • Abscess (infection)
  • Parathyroid disease
  • Trauma
  • Reiter syndrome
  • Ankylosing spondylitis
  • Psoriasis

Sacroiliac Joint Fusion!!navigator!!

mnemonic: CARPI

  • Colitic spondylitis
  • Ankylosing spondylitis
  • Reiter syndrome
  • Psoriatic arthritis
  • Infection (TB)

Widened Symphysis Pubis!!navigator!!

mnemonic: EPOCH

  • Exstrophy of the bladder
  • Prune belly syndrome
  • Osteogenesis imperfecta
  • Cleidocranial dysostosis
  • Hypothyroidism

Destructive Sacral Lesion!!navigator!!

mnemonic: SPACEMONG

  • Sarcoma: chondrosarcoma
  • Plasmacytoma
  • Aneurysmal bone cyst
  • Chordoma
  • Ependymoma, myxopapillary
  • Metastasis
  • Osteomyelitis
  • Neuroblastoma
  • Giant cell tumor

Sacral Tumor!!navigator!!

Sacral Bone Tumor

  1. BENIGN
    1. Giant cell tumor (2nd most common primary)
    2. Aneurysmal bone cyst (rare)
    3. Cavernous hemangioma (very rare)
    4. Osteoid osteoma / osteoblastoma (very rare)
  2. MALIGNANT
    1. Metastases (most common sacral neoplasm):
      • hematogenous: lung, breast, kidney, prostate
      • contiguous: rectum, uterus, bladder
    2. Plasmacytoma, multiple myeloma
    3. Lymphoma, leukemia
    4. Chordoma (most common primary)
    5. Sacrococcygeal teratoma
    6. Ewing sarcoma (rare)

Sacral Canal Tumor (less common)

  1. BENIGN
    1. Neurofibroma: multiple suggestive of NF
    2. Schwannoma (rare)
    3. Meningioma (very rare)
  2. MALIGNANT
    1. Ependymoma
    2. Drop metastases
    3. Carcinoid tumor

Outline