Non-Hodkin's lymphoma of the frontal sinus

Primary frontal sinus Non-Hodgkin's lymphoma (NHL) is an extremely rare condition with 20 cases published in the existing literature to date. We describe a 64-year-old patient who presented with right orbital pain, severe headache and diplopia. He was initially diagnosed with acute exacerbation of chronic rhinosinusitis and responded well to antibiotic treatment, but his symptoms returned. The diagnosis of frontal sinus NHL was made only after functional endoscopic frontal sinus surgery was performed in general anaesthesia. A tumor mass, which was filling the entire right frontal sinus, was completely removed and sent to histopathological examination. The patient was finally diagnosed with diffuse large B-cell lymphoma of the frontal sinus and referred to the haematology department for tumor staging and chemotherapy. This case emphasizes the importance of early clinical suspicion and diagnosis, which leads to early treatment and better prognosis.