[A Case of Intravascular Lymphoma Mimicking Acute Sinusitis in Which the Outcome was Unfortunate].

Intravascular large B-cell lymphomas (IVLBCL) are a rare and aggressive non-Hodgkin Lymphoma characterized by proliferation of malignant lymphoid cells into the small blood vessels of the whole body. Making a diagnosis is very difficult due to the lack of mass formation and lymph node enlargement, resulting in a poor prognosis. We report herein on a case of IVLBCL which was proved by a biopsy of the nasal mucosa during endoscopic sinus surgery. A 77-year-old woman was admitted with complaints of headache, rhinorrhea, and fever. Computed tomography showed a shadow in the ethmoid sinus on both sides but without polyps. We suspected acute sinusitis and started therapy, however, high fever persisted with worsening of the patient's general condition. Pathological analysis of biopsy specimens from the nasal cavity and sinuses revealed proliferation of malignant lymphoid cells into the small blood vessels and the final diagnosis was IVLBCL. Chemotherapy was initially effective for her general condition but she died 13 months after the first visit. It is important to suspect IVLBCL, if there is any deterioration of the patient's general condition and persistence of the disease against treatment. The nasal cavity is recommended as a site of random biopsy because of its rich population of small blood vessels.