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oncology

Fibrous Dysplasia

intermediate
6 min
28 marks
6 questions
Clinical Scenario
A 25-year-old woman presents with progressive right hip pain over 5 years. She walks with a limp. On examination, she has a leg length discrepancy of 3cm (right shorter). X-ray shows an expansile lesion in the proximal femur with a "ground-glass" appearance and coxa vara deformity (shepherd's crook). She has no skin lesions or endocrine abnormalities. Laboratory tests including calcium, phosphate, and alkaline phosphatase are normal.
AP radiograph of the proximal femur demonstrating monostotic fibrous dysplasia. The lesion shows characteristic 'ground-glass' or 'smoky' appearance due to fibrous tissue with immature bone. There is expansion of the proximal femur with the classic 'shepherd's crook' deformity (coxa vara). The lesion has well-defined margins with no periosteal reaction. This is the most common location for symptomatic monostotic fibrous dysplasia.
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AP radiograph of the proximal femur demonstrating monostotic fibrous dysplasia. The lesion shows characteristic 'ground-glass' or 'smoky' appearance due to fibrous tissue with immature bone. There is expansion of the proximal femur with the classic 'shepherd's crook' deformity (coxa vara). The lesion has well-defined margins with no periosteal reaction. This is the most common location for symptomatic monostotic fibrous dysplasia.

Image source: Open Access medical literature (NIH/PubMed Central) • CC-BY License

Questions

Question 1 (4 marks)

Describe the clinical and radiographic features of fibrous dysplasia.

Question 2 (5 marks)

What are the associated syndromes?

Question 3 (6 marks)

Describe the management options.

Question 4 (5 marks)

What are the complications?

Question 5 (4 marks)

How do you differentiate fibrous dysplasia from other lesions?

Question 6 (4 marks)

Discuss outcomes and prognosis.

Exam Day Cheat Sheet

Must Mention

  • •Ground-glass or smoky appearance
  • •Shepherd's crook = coxa vara (proximal femur)
  • •GNAS mutation (mosaic)
  • •Monostotic 70-80% vs polyostotic
  • •McCune-Albright: FD + café-au-lait + endocrine
  • •Malignant transformation <1%

Common Pitfalls

  • •Confusing with osteofibrous dysplasia
  • •Missing McCune-Albright
  • •Wrong transformation rate
  • •Thinking curettage is curative
  • •Wrong café-au-lait features
  • •Missing endocrine workup