Phenytoin-induced gingival enlargement — ORE Part 1 MCQ

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ModeratePeriodontologyPhenytoin-induced gingival enlargementORE Part 1

A 42-year-old patient who has been taking phenytoin for epilepsy develops gradually progressive, firm gingival enlargement, most marked around the anterior teeth. Plaque deposits and gingival bleeding are also present. The enlargement began after phenytoin was commenced. What is the most likely diagnosis?

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Correct answer: C — Phenytoin-induced gingival enlargement

**E. Phenytoin-induced gingival enlargement** is correct. The decisive features are gradual onset after starting phenytoin and firm, fibrotic enlargement that is prominent in the anterior dentition. UK phenytoin SmPCs list gingival hyperplasia/enlargement as an adverse effect; plaque and poor oral hygiene can contribute to its severity, so bleeding and deposits may coexist without being the primary diagnosis. Plaque-induced gingivitis causes erythema, oedema and bleeding but does not usually produce this characteristic fibrotic drug-related overgrowth. Acute herpetic gingivostomatitis causes painful acute ulcerative/vesicular disease. Leukaemic infiltration is typically boggy, swollen and prone to spontaneous bleeding, with relevant systemic features. Pregnancy-associated enlargement requires the relevant physiological context and is generally more inflammatory than the fibrotic phenytoin pattern.

Reference: Electronic Medicines Compendium. Phenytoin Hospira 50 mg/ml Injection BP: Summary of Product Characteristics, section 4.8 Undesirable effects, 2026. https://www.medicines.org.uk/emc/product/3794/smpc