Hypophysitis is an inflammation of the pituitary gland. It is a condition that can cause a variety of symptoms due to the pituitary gland’s role in producing hormones that regulate various bodily functions.



This report pertains to a gentleman who presented with hyponatremia. He was found to have hypopituitarism that was the underlying cause of his hyponatremia. MRI showed an enlarged posterior pituitary and thickened stalk. This is illustrated in Figure 1. He was diagnosed with presumed lymphocytic infundibulohypophysitis. He was treated with two courses of high dose prednisone. He was also started on hormone replacement therapy including treatment for diabetes insipidus. The inflammation of the stalk and posterior pituitary regressed. The remarkable changes are illustrated in Figure 2. Imaging of his pituitary nine months later showed recurrent thickening of the infundibulum suggesting that his disease had reactivated. This is demonstrated in Figure 3. A third course of pulsed steroid therapy has been recommend.
Several conditions can cause inflammation and thickening of the infundibulum and posterior pituitary gland. These include the autoimmune conditions known as lymphocytic hypophysitis, which mostly affects the interior pituitary gland, lymphocytic infundibulohypophysitis, which affects the anterior and posterior gland, and infundibuloneurohypophysitis that affects only the posterior pituitary gland. Other similar conditions include Langerhan cell histocytosis, sarcoidosis, fungal infections, tuberculosis, and IgG4 mediated-disease. Some patients develop tumors of the infundibulum, including stalk pituitary adenoma, craniopharyngioma, germinoma, and various neurohypophyseal tumors. Others have metastatic disease to the infundibulum. Central nervous system lymphoma can also manifest as inflammation in this region. Pituitary physicians consider all of these possible conditions as treatment varies depending on the underlying cause. In many cases, biopsy is preferred to secure the underlying diagnosis. In lieu of biopsy, and in the absence of other associated conditions or clinical clues, the diagnosis of lymphocytic hypophysitis is often made.
Hypophysitis is common in the later stages of pregnancy, but can occur in both men and women at any age.
Treatment usually involves pulsed steroids, in the form of prednisone 0.5 mg per kilogram per day for 4 to 6 weeks. Imaging three months later will usually give an idea as to whether or not the patient responded to treatment. Some patients, such as this one, often require multiple treatments. If three treatments are not successful then patients can be referred to the Neuroinflammatory disorders clinic to be treated with drugs that are similar to those used to treat multiple sclerosis. I have had several patients who have received an annual infusion of rituximab that has maintained control of their disease. Curiously, I have seen patients respond with a dramatic reduction in inflammation on replacement doses of steroid hormones to treat their central adrenal insufficiency.
In most cases, pituitary hormone deficits persist, but I have seen patients enjoy full recovery of anterior pituitary functions. I can’t recall seeing full resolution of diabetes insipidus in any of my patients.
The end result of lymphocytic hypophysitis is often an empty sella. Whenever an empty sella is seen in a patient who has hypopituitarism then it must be considered that they may have had hypophysitis, Sheehan syndrome, or some other disease process that led to the empty sella and pituitary dysfunction.
A guide to evaluating the size of the infundibulum is as follows: at the top part near the median eminence of the hypothalamus it should be no wider than 3 mm; at the junction with the pituitary gland, it should be no wider than 1 mm; in the middle of these two regions, it should be no wider than 2 mm. 3-2-1……easy enough!
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