[Syphilitic chancre in the mouth: an unusual location. Case report].

Primary syphilis is characterized by the development of the syphilitic chancre, which is the first manifestation of syphilis in up to 60% of cases. Extragenital presentation is rare, with only 12-14% of all cases, and of these between 40-70% occur in the mouth, being the lips the most frequent location. Oral manifestations can represent a diagnostic challenge due to its wide spectrum of clinical presentations.