lymphocytic (autoimmune) hypophysitis

Etiology

• autoimmune in association with other autoimmune endocrinopathies
• generally occurs during or after pregnancy
• immune checkpoint inhibitors
  • nivolumab, pembrolizumab, ipilimumab, tremelimumab

Epidemiology

• rare
• affects adults
  • cancer patients treated with immune checkpoint inhibitor
• predominantly affects women, especially during pregnancy & post-partum

Pathology

• pituitary infiltration with lymphocytes & plasma cells
• fibrosis & hypopituitarism
• symmetrical enlargement of the sellar contents
• anti-pituitary antibodies (not routinely measured)

Clinical manifestations

• hypopituitarism
  • ACTH deficiency resulting in adrenal insufficiency
    • hypotension
• hyperprolactinemia may occur
• diabetes insipidus may occur
• symptoms of a mass lesion including visual defects may occur

Laboratory

• serum ACTH, serum cortisol (AM cortisol)
• serum TSH, serum T4, free T4
• serum IGF1

Radiology

• MRI may show homogeneous & symmetric mass of the sella turcica

Complications

• adrenal insufficiency is a major cause of morbidity & mortality
• visual field defects

Differential diagnosis

• prolactinoma
• Sheehan's syndrome

Management

• neurosurgery
  • exploration may be needed for diagnosis
  • visual field defects
• hormone replacement as needed
  • hydrocortisone
  • thyroxine
  • estrogen
  • growth hormone
• prognosis:
  • size of pituitary mass often decreases over time

More general terms

• hypophysitis
• autoimmune disease
• pregnancy disorder; obstetric disorder; pregnancy complication

Additional terms

• diabetes insipidus (DI)
• hyperprolactinemia
• hypopituitarism
• pituitary adenoma/prolactin secreting (prolactinoma)
• sella turcica (hypophyseal fossa)
• Sheehan's syndrome