Bone: Practice Question

Osteoid osteoma and osteoblastoma histologically resemble each other with a proliferation of osteoid tissue surrounded by vascular fibrous stroma and perilesional sclerosis. What are the dimensions used to differentiate these two tumors?
  1. Osteoid osteoma < 2.0 cm, Osteoblastoma ≥ 2.0 cm
  2. Osteoid osteoma > 2.0 cm, Osteoblastoma < 1.5 cm
  3. Osteoid osteoma > 2.0 cm, Osteoblastoma < 2.0 cm
  4. Osteoid osteoma < 2.0 cm, Osteoblastoma > 5.0 cm
  5. Osteoid osteoma < 1.0 cm, Osteoblastoma > 3.0 cm
Show Answer and Explanations

Osteoid osteoma < 2.0 cm, Osteoblastoma ≥ 2.0 cm — Correct answer

Correct. Osteoid osteoma is typically less than 2.0 cm and osteoblastoma is typically greater than 2.0 cm. Osteoblastomas also tend to show more osteoid production and vascularity. Most patients are under age 25. Classically, osteoid osteoma is very painful and is relieved with salicylates or NSAIDs.

Osteoid osteoma > 2.0 cm, Osteoblastoma < 1.5 cm

Incorrect. Osteoid osteoma is typically less than 2.0 cm and osteoblastoma is typically greater than 2.0 cm.

Osteoid osteoma > 2.0 cm, Osteoblastoma < 2.0 cm

Incorrect. Osteoid osteoma is typically less than 2.0 cm and osteoblastoma is typically greater than 2.0 cm.

Osteoid osteoma < 2.0 cm, Osteoblastoma > 5.0 cm

Incorrect. Osteoid osteoma is typically less than 2.0 cm and osteoblastoma is typically greater than 2.0 cm.

Osteoid osteoma < 1.0 cm, Osteoblastoma > 3.0 cm

Incorrect. Osteoid osteoma is typically less than 2.0 cm and osteoblastoma is typically greater than 2.0 cm.

Summary

Summary: osteoid osteoma: < 2.0 cm; osteoblastoma: ≥ 2.0 cm
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