Tacrolimus-induced plexopathy.

A 49-year-old woman developed a painful right foot drop that progressed to severe lumbosacral plexopathy, resulting in the inability to walk or stand independently. She had a history of juvenile cystinosis requiring renal transplantation and was taking lifelong immunosuppression (tacrolimus). She also had a monoclonal gammopathy of undetermined significance and diabetes. Extensive investigations, including bone marrow and superficial peroneal nerve biopsy, were non-diagnostic. Her neuropathy progressed despite corticosteroids, involving the upper limbs and causing complete loss of upper limb function. A further brachial plexus biopsy was also non-diagnostic. Tacrolimus was switched to sirolimus after which her pain resolved with functional improvements. Tacrolimus-associated plexopathy is rare but should be considered in patients who have undergone a transplant presenting with progressive neuropathy.