INTRODUCTION: Lymphoma of the extranodal NK/T nasal type is an extremely rare disease of undefined etiology, more prevalent among men 40-50 years of age, and probably related to contact with the Epstein-Barr virus. According to the REAL (Revised European-American Lymphoma) classification, it is called angiocentric T lymphoma, but can also be known as midline malignant reticulosis or lethal midline granuloma. Characterized by aggressive behavior, it is lethal in most cases. OBJECTIVE: To describe a case of extranodal non-Hodgkin's lymphoma of the nasal type treated the Department of Otolaryngology of the General Hospital Socor in Belo Horizonte, Minas Gerais, Brazil. CASE REPORT: A male patient, aged 46, visited our clinic because of chronic nasal obstruction and recurrent sinusitis. Anterior rhinoscopy showed an obstructive nasal septum deviation to the right confirmed by videofibronasolaryngoscope and mucopurulence in the right middle meatus. A CT scan of the sinuses identified the presence of soft tissue density in proximity to the right nasal septum and aerated middle conchae. The surgical and pathological examination and immunohistochemistry revealed a diagnosis of extranodal T/NK cell lymphoma, nasal type. The patient was successfully treated after early identification of tumor while still in stage IA, underwent tumor resection and radiation therapy, and has evolved with a good clinical response. Twelve months after diagnosis, he has been followed and monitored by the oncology and otolaryngology departments without signs of recurrence to date. Conclusions: The professional otolaryngologist should be alert to the existence of lymphomas among sinonasal diseases. Early diagnosis is crucial for appropriate treatment, improved patient survival, and response to therapies for the disease.