Diabetes insipidus due to herpes encephalitis in a patient with diffuse large cell lymphoma. A case report.

The major causes of central diabetes insipidus are neoplastic or infiltrative lesions of the hypothalamus or pituitary, severe head injuries and pituitary or hypothalamic surgery. Central diabetes insipidus caused by viral infections has been rarely reported in immunosuppressed patients, such as those with acquired immunodeficiency syndrome or Cushing's syndrome. We report the case of a 48-year-old woman suffering from diffuse large cell lymphoma, who developed hypotonic polyuria, hypernatriaemia and somnolence after the first course of chemotherapy with CHOEP and rituximab. Diabetes insipidus was diagnosed by low urine osmolarity and an undetectable vasopressin concentration. MRI revealed no pituitary abnormalities but encephalitis, and lumbar punction confirmed herpes zoster infection. To the best of our knowledge this is the first description of central diabetes insipidus in a lymphoma patient caused by an opportunistic CNS-infection.