Nasal T/NK-cell lymphoma is a rare and aggressive neoplasm, frequently associated with the Epstein-Barr virus. It shows a predilection for midline facial structures, with locally destructive behavior and poor prognosis. Initial manifestations include nasal obstruction, epistaxis, and facial edema. Although secondary involvement of the palate due to tumor expansion is relatively common, lip infiltration is rare and scarcely reported. Early recognition of oral manifestations is crucial for therapeutic decision-making.

To report a case of upper lip infiltration by nasal T/NK-cell lymphoma, highlighting the role of dental examination in identifying tumor extension.

A 73-year-old male patient, diagnosed with nasal T/NK-cell lymphoma and undergoing second-line treatment for one month, was referred to the Dentistry Department due to complaints of oral lesions and pain while eating. Clinical examination revealed swelling of the left midface involving the upper lip. Intraoral examination showed a purplish lesion on the hard palate with a fibroelastic consistency, and two ulcers on the upper labial mucosa: one superficial, approximately 1 cm in diameter, and another deeper, about 0.5 cm in depth and 1.5 cm in length. When the lip was at rest, tooth 12 was observed to penetrate the deeper ulcer area (corresponding to the region of labial edema). Initial diagnostic hypotheses included edema due to venous obstruction or lip infiltration by lymphoma. Computed tomography revealed an expansive, infiltrative lesion in the nasal cavity, involving the paranasal sinuses, nasopharynx, left orbit, malar region, nasal dorsum and alae, extending to the upper lip. These findings confirmed that the labial lesion was caused by tumor infiltration with epithelial disruption.

This case illustrates the invasive potential of nasal T/NK-cell lymphoma and reinforces the importance of dental examination in detecting lesions that indicate disease extension. Integrated evaluation by medical and dental teams is essential for accurate diagnosis and effective symptom management, contributing to improved patient quality of life.