Case report 836: Malignant large cell lymphoma of sacrum.

We present a case of PLB found in the sacrum in an HIV-seropositive patient who had low back pain radiating to the lower extremities. To the best of our knowledge this is the first report of this kind. Multiple imaging techniques, including MRI, could not reliably differentiate between neoplasm and infection. Both processes were considered since the patient was not only HIV-seropositive but also was an intravenous drug abuser and had a history of TB. The biopsy revealed diffuse large cell lymphoma typical of AIDS patients. The unusual location of PLB in our patient is a characteristic feature of lymphoma in patients with AIDS and our case should increase awareness among clinicians and radiologists of this possibility.