A 37-year-old woman was referred by her otorhinolaryngologist to the Center for Diagnosis of Oral Diseases at the Federal University of Pelotas Dental School, Pelotas, Brazil, with the symptom of painful lesions in the oral cavity. The lesions had first appeared 1 month previous and had increased in size in the past week. Her general practitioner had prescribed azithromycin, cephalexin, and potassium penicillin G for suspected tonsillitis, with no clinical improvement. The patient also complained of dry cough, weakness, and mild fever. Ethical approval was obtained from the Pelotas Dental School ethics committee, and the patient provided written informed consent for her inclusion in this case study. Dr. Flores is a professor, Department of Dentistry, Oral Medicine and Oral Pathology, Federal University of Juiz de Fora, Campus Governador Valadares, Governador Valadares, Minas Gerais, Brazil. Dr. Alves de Mesquita is a professor, Dental School, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil. Dr. Uchoa Vasconcelos is a professor, Department of Semiology and Clinics, Federal University of Pelotas, Pelotas, Rio Grande do Sul, Brazil. Dr. Chaves Tarquinio is a professor, Department of Semiology and Clinics, Federal University of Pelotas, Pelotas, Rio Grande do Sul, Brazil. Dr. Neutzling Gomes is a professor, Department of Semiology and Clinics, Federal University of Pelotas, Pelotas, Rio Grande do Sul, Brazil.