Malignant lymphoma occurs fairly frequently in the oral cavity, but is relatively rare in the mandible. We report a case of malignant lymphoma arising from the middle of the alveolar bone of the mandible. The patient was a 38-year-old man who had a swelling on the middle of the lower alveolus. Histopathological examination of a resected specimen was performed several times, but failed to prove malignant lymphoma. Southern-blot analysis disclosed the clonality of B-cells. We assessed the patient's overall clinical progress and decided to reexamine the surgical specimen. This led to a diagnosis of diffuse large B-cell lymphoma, Stage I E according to the Ann Arbor classification. The patient received combination treatment consisting of chemotherapy with CHOP (R-CHOP) and radiotherapy. There have been no signs of recurrence during the 27 months since treatment.
