Metabolic Bone Diseases - NEET PG Radiology

Metabolic bone diseases are a group of disorders that affect the skeletal system and result in changes to bone structure and function. These diseases can be challenging to diagnose and manage, making them a crucial topic in radiology.

In the case of metabolic bone diseases, radiology plays a critical role in diagnosing and monitoring these diseases.

Let’s learn more about metabolic bone diseases and how radiology allows doctors  to diagnose and manage these conditions effectively.

• Hyperparathyroidism (Primary)

• Pathognomonic Features
  • At 2^nd& 3^rd proximal / mid phalanges on Radial aspect: Subperiosteal resorption
• In skull :Salt & pepper skull appearance

       Loss of lamina dura Normal lamina dura

• Multifocal irregular lytic lesions scattered throughout body in metaphysis k/a “Brown tumors/Osteitis cystica fibrosa”

Important Information

• Brown tumors : Bleeding occurs within them resulting in hemosiderin deposition 

Secondary hyperparathyroidism

• Chronic kidney disease →↓Ca2+, ↑PO3 → HPT (2°)
• Hallmark finding : Sclerosis
• Alternative bands of sclerosis & osteopenia: Rugger jersey spine
• Knee & wrist : Calcification of meniscus k/a chondrocalcinosis

Important Information

• Chondrocalcinosis
  • 2°HPT
  • Pseudo gout (due to calcium pyrophosphate deposition)
    • Wrist : Triangular fibrocartilage calcification 
    • Knee: Meniscus calcification 

Paget’s Disease

• May have visual loss, hearing loss (because cranial nerves getting compressed)
• Sclerotic phase
  • Skull markedly enlarged with multiple sclerotic spots :Cotton wool skull
  • ↑Hat size: Tam O’ Shanter sign
• Lytic phase

• Osteoporosis circumscripta [large area of decreased bone density]
• In long bones 

• Lysis with advancing edge :Blade of grass / candle flame sign
• Spinal manifestation

• Peripheral sclerosis, central osteopenia: Picture frame vertebra
• Ivory vertebra

Important Information

• Ivory vertebra
  • Lymphoma 
    • Hodgkin 
  • Sclerotic metastasis
    • Prostate : male
    • Breast : female
  • Paget’s disease
  • In case of treated TB

• In bone scan

• Tc99m with MDP (Methyl Diphosphonate) [Picks up new bone formation area]
• “Mickey Mouse sign” in vertebra
• “Lincoln sign” in mandible

Mickey Mouse Sign

• USG LL → Sapheno femoral junction [GSV, SFV, SFA]
• USG Antenatal→ Anencephaly 
• Bone scan → Paget’s disease
• Brain MRI → Midbrain atrophy in case of PSNP

Acromegaly

• Due to increased growth hormone (after growth plate fusion)
• Over growth in distal phalanges : “Spade phalanx”
• Gross increase in heel pad thickness
  • > 23 mm in female
  • > 25 mm in male
• In skull
  • Widened sella
  • Prognathism
  • Enlarged sinuses
  • Thick bones, PNS

Langerhans Cell Histiocytosis

• Multisystemic disorder 
• Child  with multiple bone swelling, multiple lymph nodes, multiple skin lesions
• In skull
  • Lytic lesion: Geographical with beveled margin (differential destruction of outer & inner table)
• Spine
  • One of the Vertebra completely destroyed :“Vertebra plana”

Important Information

• LCH : MC cause of vertebra plana in children
• Ewing sarcoma, lymphoma, leukemia can also cause vertebra plana

• Mandible
  • “Floating teeth sign” (due to multiple erosion in mandible)

Radiology Related Articles:

Multiple Myeloma

• Multiple punched out lesion Aka Raindrop appearance [Also seen in lytic metastasis]

Sturge – Weber syndrome 

• Complete cerebral atrophy with tram track calcification which leads to refractory seizure 
• Port wine stain
• MC affected: Ophthalmic branch of Trigeminal nerve
• Congenital glaucoma (+)

Hemolytic Anemia

• Sickle cell anemia, Thalassemia
• Hair on end / Crew cut appearance 

Raised ICP

• Copper beaten sign
• Earliest sign on X-ray
  • Children: Sutural diastasis (Sutural widening )
  • Adults : Dorsum sella erosion

Osteopetrosis

• Congenital dysplasia
• Child with hepatosplenomegaly having pancytopenia
• Diffuse ↑ density
• Bone within Bone appearance / Sandwich sign 

Osteoporosis

• Diffuse ↓ density
• End plates compressed :“Codfish appearance ” [due to weak bone & weight of the body]
• Important Information
• Codfish appearance also seen in Osteomalacia (Vit D def. in adults)
• IOC: Dexa Scan (Dual energy X-ray absorptiometry)
  • If we compare the bone mineral density of the patient with young adult : T score
  • If we compare the bone mineral density of the patient with the same aged person : Z-score
  • WHO scoring used T-score
    • +2 to -1 : Normal 
    • -1 to -2.5 : Osteopenia
    • < -2.5 SD : Osteoporosis

Rickets

• Child with widening of joints predominantly wrist, ankle 
• Vit D deficiency
• Earliest finding: Increased growth plate / Zone of provisional calcification 
  • Due to decreased vitamin D →↓Ca2+ 
  • Unmineralized osteoid accumulates near growth plate
• Seen in Metaphysis: Cupping, Splaying, Fraying (irregularities)
• Sign of healing rickets

• White metaphyseal line

Important Information

• White metaphyseal line
  • Healing rickets
  • Lead poisoning 
  • Treated Leukemia
  • Scurvy

Scurvy 

• Vitamin C deficiency
• Bone density decreased
• Frenkel’s white line
• Wimberger sign [Epiphyseal sharp margin]
• Pelkan spur (metaphyseal projection)
• Trummerfeld zone (Translucent zone above white line)
• Subperiosteal hemorrhage
  • Very painful [Scurvy is known as Pseudo paralysis state]

Chronic Osteomyelitis

• Central white dead bone (no demineralization) → Sclerotic k/a Sequestrum
• Surrounding translucent granulation → Involucrum
• Defect through which the pus comes out → Cloaca (then will have draining sinus)

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