Quiz page answers April 2005

Article Outline

 

A 49-year-old woman presented with subacute onset of lethargy, gait disturbance, and fever. Serum electrolytes were normal, and her creatinine level was 1.53 mg/dL (135 μmol/L). Ten months prior, she received a cadaveric renal transplant complicated by severe acute vascular rejection, which was refractory to pulse steroid, antilymphocyte globulin, and monoclonal antibody (OKT3) therapy given sequentially. This rejection was finally reversed by “rescue” therapy with tacrolimus, and her serum creatinine level settled in the fourth week at 1.58 mg/dL (140 μmol/L) while she was receiving prednisolone, mycophenolate mofetil, and tacrolimus. She developed cytomegalovirus (CMV) disease in the second month, which responded to ganciclovir. She then developed CMV retinitis, which required further courses of ganciclovir therapy in the ensuing months.

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• Figure 38A. 

  What do you observe on this computed tomographic image (with contrast) of the brain? What are your differential diagnoses?

• This scan of the brain reveals a nonenhancing hypodense lesion occupying the right frontoparietal, internal capsule and basal ganglia region, with surrounding cerebral edema, and a 2-cm contrast-enhancing lesion in the left periventricular region. Differential diagnoses: pyogenic brain abscess, toxoplasmosis, and neoplasm. Histology of brain biopsy showed diffuse large B-cell lymphoma.

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• Figure 38B. 

  The patient then complained of graft tenderness. What do you observe on this computed tomographic image (with contrast) of the graft kidney? What is your final diagnosis?

• This scan of the graft kidney shows a 4-cm nonenhancing mass lesion at its inferolateral aspect. Intralesional needle aspirate and biopsy under ultrasound guidance revealed lymphoid cells that expressed B-cell but not T-cell markers. In situ hybridization demonstrated the presence of Epstein-Barr virus-encoded RNA (EBER).

Final diagnosis: Posttransplantation lymphoproliferative disorder (PTLD) involving the brain and the allograft.

Brief discussion: PTLD is defined as the presence of an abnormal proliferation of lymphoid cells, mostly of the B lineage, after organ transplantation. It is thought to occur when there is an imbalance between the virally driven proliferation of B cells infected by Epstein-Barr virus and the host T-cell responses. Predisposing factors include heavy immunosuppression and infection by the immunomodulatory CMV. Common sites of involvement include the gastrointestinal tract, central nervous system, and the allograft itself. To our knowledge, the simultaneous occurrence of PTLD in the allograft and the central nervous system is exceedingly rare. In the index patient, the risk factors for PTLD include heavy immunosuppression and a prolonged history of CMV disease.

Case provided by Sydney Tang, MD, and Kar Neng Lai, MD, DSc, Department of Medicine, University of Hong Kong, Queen Mary Hospital, Hong Kong.

If you have an interesting case you would like to submit for consideration, please go to http://ajkd.edmgr.com to do so.