Abstract: A 33-year-old woman presented with a 1-year history of recurrent herpes simplex lesions involving the mucocutaneous junction of the upper lip, complicated by recurrent ulceration and post-inflammatory hyperpigmentation over the previous 6 months. Histopathological findings revealed variably sized basophilic tumor nests within the dermis, featuring peripheral palisading tumor cells and stromal retraction spaces, with central necrosis in some nests. Correlating with clinical manifestations, a diagnosis of nodular basal cell carcinoma was maded. The patient had no chronic ultraviolet exposure history or family history of malignant neoplasms. We hypothesize that tumor development is attributed to chronic inflammatory stimulation secondary to recurrent labial herpes simplex virus infection, aberrant tissue repair after repetitive skin injury, and Wolf's isomorphic response. The lesion underwent complete surgical excision, with adjuvant photodynamic therapy administered postoperatively.No recurrence was observed at the 6-month follow-up.

Key words: basal cell carcinoma, herpes simplex, isomorphic response, dermatoscopy