Lymphocytic adenohypophysitis (LYH) is a rare disease of the pituitary gland that predominantly affects young women during pregnancy or postpartum. Symptoms in 80% of cases are due to of pituitary dysfunction, which can vary from panhypopituitarism to partial hypopituitarism to single hormone deficiency. Since 1962 when the disorder was first described, less than 150 cases have been reported. The true prevalence of LYH is underestimated probably because of poor recognition of this disorder by physicians. Early diagnosis is essential because untreated disease can be fatal. Although considerable evidence supports an autoimmune basis for LYH, there is no definitive proof. Almost 30% of patients have a history of coexisting autoimmune diseases. When 2 or more autoimmune diseases are identified in the same patient, the condition is now considered to be a component of autoimmune polyendocrine syndrome. Lymphocytic adenohypophysitis is often associated with Hashimoto thyroiditis or Graves disease. Infiltration of the gland by inflammatory cells produces a nonneoplastic pituitary mass composed of lymphocytes and plasma cells; this inflammatory mass is a common feature of the disease.
Lymphocytic adenohypophysitis can be suspected in women who present during the third trimester of pregnancy or in the early postpartum period with pituitary masses and/or hypopituitarism, especially in those who also have other autoimmune diseases or unusual patterns of hormone deficiencies. Often there is failure of lactation or menses after delivery in these women. Symptoms related to the pituitary mass can include visual disturbances or severe headaches. Other symptoms related to hypopituitarism may be noted. Hormonal-related symptoms can include amenorrhea, galactorrhea, anorexia, and fatigue. The most frequent pituitary hormone deficiency, adrenocorticotropin deficiency, is present in about 65% of cases.
A histopathologic study by pituitary biopsy is the criterion standard for the diagnosis of the disease. Lymphocytic adenohypophysitis can mimic a pituitary adenoma. Current imaging techniques are often inadequate to distinguish between an LYH-related mass and the tumor. The natural history of LYH is unclear; spontaneous recovery of pituitary function with mass resolution can occur, and the disease may recur up to 2 years after the time of original diagnosis. Death is usually inevitable when there is complete pituitary cell destruction with irreversible hypopituitarism.
Appropriate management is controversial. Patients with LYH require replacement therapy for deficient hormones. Persistent mass reduction can be achieved by glucocorticoids, methotrexate, or azathioprine, and occasionally by dopamine agonists, pituitary surgery, or pituitary radiotherapy. Patients with a presumed diagnosis of LYH should be observed closely. Long-term follow-up is necessary to monitor for development of other hormonal deficits.