Peripheral Ossifying Fibroma Histology — ORE Part 1 MCQ

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ModerateOral PathologyPeripheral Ossifying Fibroma HistologyORE Part 1

A 50-year-old man presents with a rapidly growing exophytic mass on the lower alveolar ridge. It is sessile, firm, and ulcerated. He wears an ill-fitting lower partial denture. Biopsy shows reactive fibrous tissue with areas of metaplastic bone formation. What is the most likely diagnosis?

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Correct answer: D — Peripheral ossifying fibroma

The diagnosis is peripheral ossifying fibroma (POF). The combination of a gingival lesion with a chronic mechanical irritant (ill-fitting denture), exophytic clinical appearance, and histological evidence of reactive fibrous tissue with bone formation is pathognomonic for POF. POF is a non-neoplastic, reactive hyperplastic lesion that exclusively arises on the gingiva and alveolar ridge. Ill-fitting dentures are a known aetiological factor. Histologically, POF characteristically contains dystrophic calcification, cementum-like tissue, and immature or mature bone within a fibrous stroma, matching the biopsy description. Option B (PGCG) would show multinucleated giant cells, not described here. Option E (SCC) would show malignant epithelial dysplasia and invasion, incompatible with "reactive fibrous tissue." Option C (osteosarcoma) is an aggressive malignancy with cytological atypia, not a benign reactive lesion. Option A (fibrous epulis) lacks the key histological feature of bone formation, which is the diagnostic hallmark of POF.

Reference: Peripheral ossifying fibroma: A 20-year retrospective study with focus on clinical and morphological features, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9445604/ (2022)