Lymphocytic hypophysitis: disease spectrum and approach to diagnosis and therapy.

Lymphocytic hypophysitis (LYH) is a neuroendocrine disorder characterized by autoimmune inflammation of the pituitary gland with various degrees of pituitary dysfunction. The histopathology consists of an initial monoclonal lymphocytic infiltrate, which can heal with minimal sequela or progress to fibrosis and result in permanent hypopituitarism. Coexistence of other autoimmune conditions is reported in 25-50% of cases and pituitary autoantibodies have been detected in up to 70% of biopsy-proven cases. The clinical presentation varies depending on the pituitary segment that is more severely affected. In lymphocytic adenohypophysitis (LAH) an early destruction of the ACTH-producing cells is characteristic. Other anterior pituitary hormones can also be affected but posterior pituitary involvement is absent or minimum. Lymphocytic Infundibuloneurohypophysitis (LINH) typically presents as acute onset diabetes insipidus (DI) with intracranial mass-effect symptoms. A combination of extensive anterior pituitary involvement and DI characterizes lymphocytic Infudibulopanhypophysitis (LIPH). The diagnosis can be challenging in many cases, because distinction from pituitary adenomas and other sellar masses is not obvious. Significant efforts have been made to identify specific serum markers, but it would seem unlikely that this approach will ever have the specificity to replace histopathological examination of a surgical specimen. Diagnostic criteria have been proposed to help in the decision-making process and to avoid, whenever possible, unnecessary invasive procedures. The therapeutic approach is controversial and, although transsphenoidal surgery is often performed, a conservative medical management is justified in many cases, given the self-limited nature of the inflammatory process. This paper reviews the etiology, epidemiology, clinical and radiological findings, diagnosis and management of LYH.