[A man with a primary diffuse B-cell lymphoma of the bone].

A 63-year-old man suffered from persistent pain in the left knee that did not respond to local injections with bupivacaine and triamcinolone acetonide. The first X-ray of the knee did not show any abnormalities, but eight months later a lytic lesion in the left tibia was seen on X-ray. A PET/CT scan and histopathologic analysis of a biopsy revealed a primary diffuse B-cell lymphoma of the bone.