Post-transplant lymphoproliferative disorder of the cauda equina in a kidney transplant recipient.

introductionPost-transplant lymphoproliferative disorder (PTLD) is a condition associated with post-transplant immunosuppression that can develop in various organs, including the grafted one. However, it has rarely been reported in nerve tissue. We encountered an unexpected case of PTLD in the cauda equina of a kidney transplant recipient who was being treated with chronic immunosuppressive therapies. CASE PRESENTATION: The patient was a 39-year-old woman in whom lower limb muscle weakness appeared and progressed rapidly 10 years after kidney transplantation for glomerulonephritis. Magnetic resonance imaging (MRI) findings were suggestive of an intradural extramedullary tumor. Diagnosis of PTLD was established on open biopsy. Culprit immunosuppressants (tacrolimus, mycophenolate mofetil, and prednisolone) were discontinued, and rituximab and radiation therapy were started. The paraplegia gradually improved after drug discontinuation, and the lesion diminished in size 3 months after this series of treatment, and finally disappeared on MRI as of 1 year after treatment. DISCUSSION: PTLD in the cauda equina is extremely rare, and only one case involving the cauda equina has been reported previously. Biopsy should be performed initially for definitive diagnosis, after which the suspected culprit immunosuppressants should be immediately discontinued.