Squamous Cell Carcinoma Developing in a Cutaneous Lichen Planus Lesion: A Rare Case

Lichen planus is a benign disorder characterized by an itchy, noninfectious skin rash. Though lichen planus is a common papulosquamous disorder affecting about 1-2% of the population, neoplastic transformation of cutaneous lichen planus lesions occurs very rarely and should be borne in mind while treating nonhealing longstanding lesions of lichen planus. Studies suggest an estimated 0.3–3% risk of malignancy in patients with oral lichen planus, however, cutaneous lichen planus does not carry an increased risk of malignant degeneration. We present a case of a 36-year-old male with a 10-year-long history of hypertrophic lichen planus who presented with a nonhealing ulcer in the left popliteal fossa. The patient underwent wide local excision with superficial skin grafting. Postoperative histopathological examination revealed verrucous squamous cell carcinoma complicating lichen planus. In view of underlying structure involvement, adjuvant radiation therapy was given. This case is being reported to emphasize the infrequent possibility of development of malignancy in cutaneous lichen planus, especially if it presents as a longstanding, nonhealing, itchy lesion with patchy areas of depigmentation in the lower limbs. 1. Introduction Lichen planus is a benign cell mediated immune response of unknown origin characterized by an itchy, noninfectious skin rash. Though lichen planus is a common papulosquamous benign disorder affecting about 1-2% of the population, neoplastic transformation of cutaneous lichen planus lesions occurs very rarely and should be borne in mind while treating nonhealing longstanding lesions of lichen planus. Studies suggest an estimated 0.3–3% risk of malignancy in patients with oral lichen planus. However, cutaneous lichen planus does not carry an increased risk of malignant degeneration and is not considered as a premalignant lesion unlike its oral counterpart. But few studies have described the occurrence of squamous cell carcinomas from longstanding, nonhealing, itchy lesions of cutaneous lichen planus of the lower limbs [1–5]. 2. Case Presentation A 36-year-old male presented with an ulceroproliferative growth in the left popliteal fossa. The lesion in the left popliteal fossa started as a hypertrophic lichen planus lesion which was diagnosed about 10 years back. He had been treated for his lichen planus lesions, but with no signs of relief. There was history of severe itching in the lesion of the left popliteal fossa. A review of the histopathological slide which was made elsewhere 2 years back from the lesion of the left popliteal