Primary Syphilitic Chancre Presenting as a Non-healing Ulcer of the Lower Lip: A Case Report

Introduction The diagnosis of primary syphilis can be challenging, as direct inoculation at non-genital sites such as the lips may result in extragenital chancres, even though the disease typically presents as a genital ulcer. Case Presentation A 32-year-old man had a lower lip ulcer that was indurated and painless for three weeks. The patient reported a history of orogenital contact with a woman 17 days before the appearance of the lip ulcer. Initially, the lesion was misdiagnosed as a traumatic ulcer and was unsuccessfully treated with topical antibiotics. Examining the lower lip revealed a single, distinct, oval ulcer with a clean base and firm induration. The submental lymph nodes showed a slight non-tender enlargement. A confirmatory Treponema Pallidum Hemagglutination Assay (TPHA) and a positive Venereal Disease Research Laboratory (VDRL) test (1/64) were found through serological testing. Human Immunodeficiency Virus (HIV) and Herpes Simplex Virus immunoglobulins (HSV IgM, IgG) were not detected. After receiving a single intramuscular dose of 2.4 million units of benzathine penicillin G, the patient recovered completely in two weeks. Conclusion Chronic indurated ulcers of the lip may have various etiologies, and the possibility of a primary syphilitic chancre, though rare, should always be considered. Awareness of this presentation is essential, as early diagnosis and appropriate treatment are crucial to prevent disease progression and transmission.