Diagnosis of septic joint in an immunosuppressed patient by twenty-four hour delayed imaging with Tc-99m HMPAO labeled white blood cell scan

A 64-year-old male with a history of allogeneic bone marrow transplantation for lymphoma 10 months earlier presented for evaluation of bacteremia. The white blood cell count was 4,400 cells/microliter with 76% neutrophils. A tagged white blood cell scan was performed to localize the infection. Images obtained 4 hours postinjection of radiolabeled leukocytes displayed no focus of infection, but delayed 24-hour images demonstrated the interval development of markedly increased activity in the left shoulder. Arthrocentesis yielded purulent fluid. We hypothesize that delayed leukocyte migration in this immunosuppressed patient might have accounted for the significant disparity between the standard and delayed scans.