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Aneurysmal Bone Cyst — MFDS Part 1 MCQ

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HardOral PathologyAneurysmal Bone CystMFDS Part 1

A 19-year-old patient presents with a rapidly enlarging, expansile multilocular radiolucency of the posterior mandible. Cross-sectional imaging demonstrates fluid–fluid levels. An incisional biopsy contains giant-cell-rich fibroblastic tissue and is initially considered possibly to represent a central giant cell granuloma. Which additional histopathological finding would most strongly support a diagnosis of aneurysmal bone cyst?

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Correct answer: D — Large blood-filled pseudocystic spaces without epithelial or endothelial lining, separated by fibrovascular septa containing osteoclast-type giant cells and reactive woven bone

Explanation lettering: E = shown as A · C = shown as B · D = shown as C · A = shown as D · B = shown as E

A is correct. An aneurysmal bone cyst characteristically contains blood-filled pseudocystic spaces that lack epithelial and endothelial lining. These are separated by fibrovascular septa containing spindle cells, osteoclast-type giant cells and variable reactive woven bone or osteoid. Rapid expansion and fluid–fluid levels support the diagnosis but are not independently specific. Option B describes the more uniform giant-cell-rich stroma of a central giant cell granuloma. Option C indicates telangiectatic osteosarcoma, in which malignant cytological atypia and malignant osteoid are decisive. Option D describes a simple bone cyst, while option E represents a true vascular lesion with endothelial-lined channels.

Reference: Nascimento SVB et al. Aneurysmal Bone Cyst in the Anterior Region of the Mandible. Head and Neck Pathology. 2024;18(1):50. https://pubmed.ncbi.nlm.nih.gov/38884839/