This is a 21-year-old woman, with no previous history of interest, who initially consulted the emergency department of her health centre due to odynophagia and fever, was diagnosed with acute pharyngitis, and was prescribed treatment with oral amoxicillin for a week. Once the treatment was completed, the patient visited her primary care physician, reporting a remission of fever but persistent odynophagia, which she related to a lesion on the left lateral edge of the tongue. Examination revealed an ulcerated lesion, whitish in colour, approximately 1 cm in diameter, on the lateral edge of the tongue, about 3.4 cm from the tip. No lymphadenopathy or other oropharyngeal lesions were found. The lesion was labelled as a lingual aphthous ulcer, in the context of a post-infectious condition, and symptomatic treatment was prescribed to alleviate the discomfort. After 15 days, the lesion did not improve, and on re-interrogation of the patient it was found that the lesion may have preceded the infectious condition, with these data the patient was referred for a biopsy of the lesion. The intraoperative biopsy diagnosed squamous cell carcinoma that reached the surgical edge. The microscopic description showed an ulcerated neoformation that infiltrated deep to the vicinity of the deep resection edge without reaching it. The neoformation consists of epithelial cells arranged in nests or cords. These cells have a low mitotic index and have a tendency to form horny globes. The diagnosis is well-differentiated squamous cell carcinoma infiltrating to the vicinity of the surgical resection margin. Subsequently, a biopsy of a cervical fibroadipose fragment containing 25 lymph nodes was performed and all 25 were negative for tumour cells. The patient underwent surgery where a functional neck dissection and a left hemiglossectomy was performed using CO2 laser. The evolution was satisfactory, being asymptomatic up to the present time and with no signs of recurrence.