Allopurinol-Induced Oral Lichenoid Drug Reaction with Complete Regression after Drug Withdrawal

Abstract

Background: Lichen planus is a chronic mucocutaneous inflammatory disease. Oral manifestations are common, and may remain exclusive to the oral mucosa without involvement of the skin or other mucosae. A differential diagnosis includes oral lichenoid drug reactions. Allopurinol, which is the first line hypo-uricemic treatment, is often quoted as being a possible offending drug, though oral reactions have rarely been reported. Case presentation: We describe a 59-year-old male gout patient, successfully treated with allopurinol, who developed acute onset of oral lichenoid lesions, involving bilaterally the buccal mucosa, the tongue and the labial mucosa. Histopathology was consistent with a lichen planus or a drug-induced lichenoid reaction. Improvement of the patient's condition after withdrawal of allopurinol confirmed the lichenoid nature of the lesion. Remission was complete after a few weeks. Discussion: Although unusual, allopurinol may induce a lichenoid drug reaction. These reactions may mimic clinically and histopathologically idiopathic lichen planus. Improvement or complete regression of the lesions may be attempted to confirm the diagnosis. According to the latest WHO recommendations, these lesions have a potential for malignant transformation.

Keywords: adverse drug reaction; allopurinol; lichen planus; lichenoid reaction; oral mucosa.

Figure 1

(a) Keratotic lesions involving the right buccal mucosa and the lower lip, with focal erythema and an ulcerated area. (b) Keratotic lesions involving the lateral border of the tongue, and the median anterior area. (c) Keratotic lesions of the left buccal mucosa and lip.

Figure 1

(a) Keratotic lesions involving the right buccal mucosa and the lower lip, with focal erythema and an ulcerated area. (b) Keratotic lesions involving the lateral border of the tongue, and the median anterior area. (c) Keratotic lesions of the left buccal mucosa and lip.

Figure 2

(a) Histopathological section showing parakeratotic partly atrophic squamous epithelium with a band-like dense inflammatory infiltrate in the superficial chorion (HE stain, ×10). (b) Higher magnification showing inflammatory lymphocytic infiltrate and apoptotic bodies in the basal layer (HE stain, ×40).

Figure 2

(a) Histopathological section showing parakeratotic partly atrophic squamous epithelium with a band-like dense inflammatory infiltrate in the superficial chorion (HE stain, ×10). (b) Higher magnification showing inflammatory lymphocytic infiltrate and apoptotic bodies in the basal layer (HE stain, ×40).

Figure 3

(a–c) Three-year follow-up showing complete healing of the right buccal mucosa and the lower lip (a), the lateral border of the tongue (b), and the left buccal mucosa and lip (c).

Figure 3

(a–c) Three-year follow-up showing complete healing of the right buccal mucosa and the lower lip (a), the lateral border of the tongue (b), and the left buccal mucosa and lip (c).