Question:medium
A 65-year-old man presents with enlarged hat size, shin pain, elevated alkaline phosphatase, and normal calcium and PTH levels. X-ray reveals mixed lytic and sclerotic bone lesions. What is the most likely diagnosis?
A 65-year-old man presents with enlarged hat size, shin pain, elevated alkaline phosphatase, and normal calcium and PTH levels. X-ray reveals mixed lytic and sclerotic bone lesions. What is the most likely diagnosis?
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Elderly patient with bone pain, enlarged skull, raised ALP, and normal calcium = Paget's disease of bone.
Updated On: May 14, 2026
- Paget's disease
- Primary hyperparathyroidism
- Osteomalacia
- Bone metastasis
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The Correct Option is A
Solution and Explanation
Step 1: Understanding the Question:
The question presents a classic case of Paget's disease of bone, evidenced by bone enlargement, localized pain, and a characteristic biochemical pattern.
Step 2: Detailed Explanation:
Paget's Disease (Osteitis Deformans): This is a disorder of bone remodeling where excessive bone resorption is followed by disorganized, excessive bone formation.
Clinical Findings:
- Skull Enlargement: Leads to the classic "increasing hat size" or "lion-like face."
- Shin Pain: Due to bowing of the tibia (sabre tibia).
Biochemical Pattern: The hallmark is a markedly elevated Alkaline Phosphatase (ALP) reflecting high osteoblastic activity, with normal serum calcium and phosphorus. This "dissociation" differentiates it from hyperparathyroidism (where calcium is high).
Radiology: Findings include the "mixed" phase (lytic and sclerotic areas). In the skull, this is known as the "cotton wool" appearance.
Complications: The most serious (though rare) complication is a transformation into Osteosarcoma.
Step 3: Final Answer:
The combination of isolated high ALP, increasing bone size, and mixed X-ray lesions is diagnostic of Paget's disease.
The question presents a classic case of Paget's disease of bone, evidenced by bone enlargement, localized pain, and a characteristic biochemical pattern.
Step 2: Detailed Explanation:
Paget's Disease (Osteitis Deformans): This is a disorder of bone remodeling where excessive bone resorption is followed by disorganized, excessive bone formation.
Clinical Findings:
- Skull Enlargement: Leads to the classic "increasing hat size" or "lion-like face."
- Shin Pain: Due to bowing of the tibia (sabre tibia).
Biochemical Pattern: The hallmark is a markedly elevated Alkaline Phosphatase (ALP) reflecting high osteoblastic activity, with normal serum calcium and phosphorus. This "dissociation" differentiates it from hyperparathyroidism (where calcium is high).
Radiology: Findings include the "mixed" phase (lytic and sclerotic areas). In the skull, this is known as the "cotton wool" appearance.
Complications: The most serious (though rare) complication is a transformation into Osteosarcoma.
Step 3: Final Answer:
The combination of isolated high ALP, increasing bone size, and mixed X-ray lesions is diagnostic of Paget's disease.
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