Fibrous Dysplasia CT Features — ORE Part 1 MCQ

Instant feedback + full explanation. One question, done properly.

ModerateRadiology & ImagingFibrous Dysplasia CT FeaturesORE Part 1

A 30-year-old patient presents with a painless bony swelling of the anterior mandible that has been slowly enlarging. CT shows a mixed radiolucent-radiopaque lesion with a 'ground glass' appearance, blending imperceptibly with surrounding bone. There is no corticated border. The inferior alveolar canal is displaced but intact. What is the most likely diagnosis?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: B — Fibrous dysplasia

The answer is **A. Fibrous dysplasia**. The ground glass appearance on CT with imperceptible blending into surrounding bone and absence of cortication is pathognomonic for fibrous dysplasia (FD). This benign fibroosseous lesion most commonly presents as a mixed radiolucent-radiopaque lesion with a ground glass pattern. The key discriminator from ossifying fibroma (option B)—the closest differential diagnosis—is the lack of cortication and well-defined borders; ossifying fibromas characteristically present with well-defined, corticated margins. Displacement of the inferior alveolar canal while maintaining cortical integrity also supports FD over malignant lesions such as osteosarcoma. Paget disease and ameloblastoma have distinct imaging patterns and are less consistent with the clinical and radiological presentation described.

Reference: Pubmed/NCBI: Fibrous dysplasia--a 13-year retrospective radiographic analysis in a south Indian population. 2011. https://pubmed.ncbi.nlm.nih.gov/21697153/; and Fibro-osseous lesions of the craniofacial skeleton: an update. 2014. https://pubmed.ncbi.nlm.nih.gov/25409854/