Primary frontal sinus lymphoma is a rare disease, with the presenting symptoms that are secondary to the tumor mass effect and often misleading. Here we describe the case of a 43-year-old male patient who presented with a 4-week history of a gradually enlarging painful diffuse swelling over the right frontal sinus region. We report the clinical presentation, differential diagnosis and treatment of the case. We also reviewed the available literature on the diffuse large B-cell lymphoma in the frontal sinus region. The article emphasizes the importance of early recognition of this rare disease.