A Case of Primary Pulmonary Epstein-Barr Virus-positive Diffuse Large B-cell Lymphoma, Not Otherwise Specified

━━ Background. Most patients with Epstein-Barr virus (EBV)-positive diffuse large B-cell lymphoma, not otherwise specified (DLBCL, NOS) are over 50 years age and have no past medical history that indicates auto-immune diseases or immunodeficiency syndromes. The disease is rare and commonly occurs in the extralym-phatic organs of elderly people. Moreover, the resemblance of its histological features to those of inflammatory disease makes it difficult to make a definitive diagnosis based on the pathological examination of tiny tissue biopsy specimens. Case. A 75-year-old man with an abnormal X-ray shadow of the chest was referred to our hospi-tal. He had no history of immunodeficiency disorders. A CT scan showed a tumor in the right upper lobe of lung. We found no histological evidence of malignancy, despite performing repeated transbronchial biopsies of the primary lesion. Meanwhile, the tumor grew. The patient underwent right upper lobectomy because the possibility of lung carcinoma could not be excluded. A pathological examination revealed the lesion to be EBV-positive DLBCL, NOS. The lymphoma spread aggressively in spite of chemotherapy, and the patient died of the disease 5 months after surgery. Conclusion. We clinicians should know that EBV-positive DLBCL, NOS can occur primarily in the lung and that its histological features can make it difficult to definitively diagnose based on the pathological examination of small biopsy samples of the diseased tissue.