Verrucous carcinoma in association with hypertrophic lichen planus.

Neoplastic transformation of lichen planus is a rare event. However, squamous cell carcinoma may develop in 0.3%-3% of patients with the oral form of the disease. On the other hand, less than 30 cases arising in cutaneous lichen planus have been reported, and only four cases of verrucous carcinoma in association with either form, one with an oral lesion and three with cutaneous lesions (one hypertrophic and one ulcerative). This report describes the unusual progression of a hypertrophic lichen planus plaque of the right leg to a verrucous carcinoma in a 40-year-old woman.