CASE 4765 Published on 17.06.2008

Cerebral post transplant lymphoproliferative disorder

Section

Neuroradiology

Case Type

Clinical Cases

Authors

V.Prakash, A.G. Muthoot

Patient

19 years, male

Clinical History
A young patient who was on long term immunosuppressive therapy post renal transplant was admitted with a three week history of generalised headaches and absence episodes.
Imaging Findings
Patient had familial membrano-proliferative glomerulonephritis needing a renal transplant aged 4years. Owing to graft failure, he had a second renal transplant aged 6 years.Following this he had been on long term immunosuppressive therapy . He had been relatively well since then.Patient admitted with a three week history of generalised headaches with absence episodes. A non-contrast CT head revealed low density lesions in Left temporal and cerebellum with no associated mass effect. A lumbar puncture was unremarkable other than a mild lymphocytosis . MRI brain matched the CT findings showing ring enhancing lesions within L superior cerebellar hemisphere and areas of enhancement in L peri-Sylvian region but also a further lesion in the L mesial temporal lobe . Differential diagnoses were lymphoma and opportunistic infection.Appearances were thought to be to Toxoplasmosis and he was started on anti-toxoplasma treatment while weaning him off the immunosuppressive therapy. CSF and serum EBV were positive. TB, HIV and other atypical and opportunistic infections were excluded. He became unwell after 2 weeks of anti-toxoplasma treatment, developing seizures and renal deterioration for which he needed intravenous antiepileptics and haemodialysis respectively. A further MRI showed progression of the lesions. This suggested a non-toxoplasma cause and a Tc-MIBI SPECT brain scan was performed, which favoured a diagnosis of PTLD. Confirmatory brain biopsy showed histological appearances of a polymorphous post-transplant lymphoproliferative disease (PTLD) which were EBV PCR positive. He was commenced on chemotherapy, whereby his symptoms gradually improved and the lesions showed MRI evidence of regression a few months later.
Discussion
Post-transplantation lymphoproliferative disorder (PTLD) has been recognized as a complication of organ and cell transplantation for more than 30 years. It is a serious disorder which has graveconsequences if not detected and treated appropriately. It is distinct from primary brain lymphomas in its clinical and imaging characteristics (1).As early recognition and treatment is imperative,an accurate definitive diagnosis is the aim. PTLD is a sequel of chronic immunosuppression and affects approximately 1% of renal transplant cases (2). Whilst most cases tend to occur within 18 months of transplantation late case do occur and are thought to be secondary to changes in immunosuppression. A strong association exists between PTLD and Epstein-Barr virus infection of the B-lymphocytes(3). In immunosuppressed individuals with intracranial lesions, the main differential diagnoses are infections (toxoplasmosis being the most common) and lymphomas. Stereotactic brain biopsy carries significant morbidity but remains the investigation of choice for definitive diagnosis of intracranial lesions. There could be an argument for using a combination of neuro-imaging, Tc-MIBI SPECT imaging with high retention index (>1.5) and positive EBV PCR in CSF to provide an accurate and early diagnosis of PTLD without the need for invasive and potentially risky procedures to aid in thediagnosis. However, further studies are recommended in this aspect, especially in view of the fact that there may be false positive results if the patient has already received prior anti-toxoplasma treatment (3).MRI imaging of the brain typically shows supratentorial multifocal discrete contrast-enhancing masses. In immunocompromised patients where post transplant lymphomas also appear as multifocal enhamcing masses , distinguishing between these two pathologies on neuroimaging alone can be challenging (4). Nuclear imaging was shown to be of use in AIDS-related primary CNS lymphoma (5). Post transplant cerebral lymphomas can be non specific, progress rapidly and despite multimodal therapysurvival may be poor (6).
Differential Diagnosis List
Post transplant Cerebral Lymphoma
Final Diagnosis
Post transplant Cerebral Lymphoma
Case information
URL: https://www.eurorad.org/case/4765
DOI: 10.1594/EURORAD/CASE.4765
ISSN: 1563-4086