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  #1  
Old 10-28-2012
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Arrow Billy Step 1 Questions # 50

A 38-year-old man who is otherwise healthy has experienced chronic leg pain for the past 4 months. On physical
examination, there is local swelling with tenderness just below the right patella. A radiograph of the right lower leg shows a
4-cm cystic area in the right tibial diaphysis without erosion of the cortex or soft-tissue mass. A biopsy specimen shows
increased numbers of osteoclasts in this lesion and fibroblast proliferation. Which of the following underlying conditions is
most likely to account for these findings?


□ (A) Secondary hyperparathyroidism
□ (B) Paget disease of bone
□ (C) Chronic osteomyelitis
□ (D) Parathyroid adenoma
□ (E) Giant-cell tumor of bone
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  #2  
Old 10-28-2012
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(A) Secondary hyperparathyroidism-------osteitis fibrosa cystica
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Old 10-28-2012
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□ (E) Giant-cell tumor of bone
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Old 10-28-2012
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i guess its B Pagets disease.

cant be Giant cell tumour as it classically involved Epiphysis of long bones.
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Old 10-28-2012
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either A or D.........but seeing her complaints doesnt seem as chronic renal failure(option A).....so will go with D...


giant cell tumor affects epiphysis.....not diaphysis

thanks
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I think it cant be A or D either as there is no erosion of the cortex. For parathyroid lesion Erosion of cortical bone is the rule.
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Old 10-28-2012
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Quote:
Originally Posted by Timmi View Post
I think it cant be A or D either as there is no erosion of the cortex. For parathyroid lesion Erosion of cortical bone is the rule.
ya you're right..but cystic area confused me(not seen in paget's i guess)....i think osteitis fibrosa cystica..fits it but due to lack of symptoms went for D.....
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Old 10-28-2012
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Will tell the answer later
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Old 10-28-2012
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I think it is a Parathyroid adenoma. Thing is the cystic lesion with osteoclasts & fibroblasts is the classic case for PTH adenomas. What really happens is that there is too much secretion of PTH so that causes too much resorption of bone and then there occur microfractures in the area of resorption. hence the influx of macrophages and the reactive fibrosis. This tumor is also known as Brown Tumor of the Bone (It is better to know alternate names, coz the exam might play word games, who knows).

Anyways, one important differential for this tumor is the giant cell tumor of bone, however, they can be distinguished by: 1) occurence in the epiphysis and metaphysis & 2) presence of (plump?) stromal cells (not fibroblasts!)

So I think I will be going for option D here
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  #10  
Old 10-28-2012
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Correct Answer D is correct

Parathyroid adenomas secrete parathyroid hormone (PTH) and cause primary hyperparathyroidism. Excessive
secretion of PTH activates osteoclastic resorption of bone. Microfractures within the areas of bone resorption give rise to
hemorrhages; this causes an influx of macrophages and, ultimately, reactive fibrosis. These lesions are cystic, and they
are sometimes called “brown tumor of bone.” Because they contain osteoclasts and fibroblasts, these lesions can be
confused with primary bone neoplasms, such as giant-cell tumor of bone. Giant-cell tumors occur in the epiphysis or
metaphysis, however, and they contain plump stromal cells, not fibroblasts. Secondary hyperparathyroidism is seen in
patients with chronic renal failure. This patient is too young to have Paget disease of bone, which may be osteolytic in its
early phase. Chronic osteomyelitis rarely produces such a discrete lesion.
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  #11  
Old 10-28-2012
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Default my answer :)

(D) Parathyroid adenoma
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my ans is pagets disease of bone
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Old 01-28-2013
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(D) Parathyroid adenoma
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