A cutaneous leiomyosarcoma arose in the upper lip skin of a 22-year-old patient. This unusual tumor was diagnosed clinically as a basal cell carcinoma although histological studies confirmed a leiomyosarcoma. The tumor was excised using Mohs technique and the wound reconstructed with a nasolabial flap and full-thickness skin graft. No recurrence or distant metastasis has appeared in a two-year follow-up.