Progressive multifocal leukoencephalopathy 10 years following transplant: 5HT receptor antagonism as an adjunct to immune reconstitution

We report a case of a patient presenting with subacute neurological symptoms 10 years postkidney transplant. Cognitive deficits included acalculia and left upper limb dysesthesia, progressing to hemiplegic upper motor neuron weakness. Investigations included an MRI with multiple FLAIR hyperintensities, while a lumbar puncture was sterile with negative flow cytometry. Ultimately, PCR testing for John Cunningham virus was positive on cerebrospinal fluid. The diagnosis of progressive multifocal leukoencephalopathy (PML) was confirmed on the basis of the above. Initially, the patient was managed with withdrawal of immunosuppressants and close observation. Mirtazapine was commenced based on case reports of successful use in non-transplant patients; the patient’s recovery was temporally related to withdrawal of immunosuppression and increasing mirtazapine dosage. The patient is currently maintained on prednisolone and mirtazapine with stable graft function and improved mobility and cognitive function.