Tumefactive demyelination, an uncommon form of tacrolimus neurotoxicity

The immunosuppressant tacrolimus (FK 506) is widely used in transplantation medicine, although it has neurotoxic side effects. The neurotoxicity of tacrolimus to the CNS consists mainly of leukoencephalopathy with clinical and radiologic features similar to posterior reversible encephalopathy syndrome (PRES).1 The neurologic symptoms and signs of leukoencephalopathy usually develop within 3 months of commencing treatment with tacrolimus.1 We describe a patient who developed tumefactive inflammatory demyelinating lesions as an atypical manifestation of tacrolimus neurotoxicity. ### Case report. A 54-year-old woman with hepatocellular carcinoma underwent cadaver liver transplantation in May 2009. After transplantation, she was treated with tacrolimus 0.075 mg/kg and mycophenolate mofetil 250 mg BID. In September 2009, she developed slurred speech and right-side weakness 2 days before admission. Brain MRI scanned 2 days after symptoms onset showed 2 large mass-like lesions in the left corona radiata and frontal lobe. The lesions were hyperintense on T2-weighted images with an open ring pattern on gadolinium enhancement (figure,A). The serum tacrolimus level was 8.5 ng/mL (therapeutic range 5.0–15.0 ng/mL). The CSF analysis showed normal cell count, but elevated total protein level (103 mg/dL). Oligoclonal bands were absent and …