A 19-year-old man on phenytoin for focal epilepsy presents with marked overgrowth of the gingiva. The histological change underlying this adverse effect is:
- A Granulomatous inflammation of the lamina propria
- B Increased fibroblast proliferation with excess collagen deposition ✓
- C Squamous metaplasia of the gingival epithelium
- D Deposition of immune complexes in the basement membrane
Correct answer: B. Increased fibroblast proliferation with excess collagen deposition
Explanation
Phenytoin-induced gingival hyperplasia is caused by stimulation of gingival fibroblasts with increased synthesis of collagen and ground substance, producing firm overgrowth that worsens with poor oral hygiene. It is reversible on stopping the drug. Inflammation, metaplasia and immune deposition are not part of the pathology, so options A, C and D are incorrect.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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