Masked Arginine Vasopressin Deficiency in a Kidney Transplant Recipient With Posttransplant Lymphoproliferative Disorder

Posttransplant lymphoproliferative disorder (PTLD) is the second most common cancer to occur after organ transplantation, accounting for approximately 20% of all cancers post kidney transplant.1 PTLD is most common in gastrointestinal tract (20%–30%), followed by central nervous system (CNS) (5%–15%), and allograft (5%).2 In rare cases, CNS-PTLD can involve the hypothalamus and pituitary gland (<0.5%).3 Clinical presentation of PTLD is nonspecific and variable, ranging from generalized fatigue to neurological symptoms such as ataxia and seizures.