Lymphocytic Hypophysitis

"So, today we're going to be talking about (LH) lymphocytic hypophysitis. It is exactly what it sounds like. It is inflammation (itis) in the hypophysis of the pituitary gland. It involves infiltration by lymphocytes. This is an autoimmune process that is idiopathic, and is associated with the postpartum period, young females, and late pregnancy. However, it can occur at any age, either gender and at any time including the non-pregnant state. So, you should bethinking about lymphocytic hypophys it is when we have an infiltrative enlargement of the pituitary gland. As you remember from prior lectures we have the ventricles here. This is the third ventricle. The floor of the third ventricle in coronal section forms the chiasm. This is the infundibulum. In the sella is the pituitary gland. So, if the pituitary gland gets bigger, it will rise out of the sella and can compress the chiasm. If it grows laterally it will go into the cavernous sinus. This is the carotid artery and the walls of the cavernous sinus. This means that it can cause a third, a fourth, a trigeminal or a sixth cranial nerve palsy. So, we can either have afferent problems from chiasmal lesion, bitemporal hemianopsia or efferent problems from diplopia in patients who have sellar lesions including lymphocytic hypophysitis. Patients often present with pan hypopituitarism but sometimes they have what looks like a prolactinoma. So, they have hyperprolactinemia which causes amenorrhea and galactorrhea in young females. However, that might just be the stalk effects. If you press on the stalk you are interrupting the dopamine signal from the hypothalamus and that produces an elevation in the prolactin level. This leads to the syndrome of amenorrhea and galactorrhea if they have a high enough prolactin level. Often they have panhypopituitarism. However, they might have an infiltration of the stalk. This normally would not occur in pituitary adenomas alone. The key differentiating feature in the right clinical setting is going to be a pituitary that is enlarged but has an atypical appearance-specifically, a lymphocytic infiltrate appearance. The treatment for this is steroids. As opposed to the surgery transphenoidal resection for pituitary adenoma, we are going to give this steroids because it's an autoimmune lymphocytic infiltration process. In the right clinical setting-for example a24 year old postpartum female who has anew onset bitemporal hemianopsia the imaging study would show a homogenous infiltrative appearance of lymphocytic hypophysitis. We are going to give this steroids. The only way to know for sure what the diagnosis is to have a biopsy. On the biopsy we usually see a lymphocytic infiltration. You should also know that we have to consider the possibility of IgG4 disease. So, in the past, lymphocytic hydpophysitis was considered idiopathic but some of these idiopathic LH cases actually have IgG4disease.Youcan look at the other video on IgG4 disease to see how that subclass restriction of immunoglobulin can infiltrate your pituitary gland. The reason this is important is that in IgG4 infiltration the "itis" can occur in other organ systems. It can cause thyroiditis, it can cause retroperitoneal disease, and it can cause orbital inflammatory pseudotumor. So, the IgG4just goes to whatever organ system it wants to go to and therefore, each subspecialty of medicine actually has its own version of orbital inflammatory pseudotumor in their organs. ENT has it in the thyroid. General surgery has it in the retroperitoneum. Every organ has its own version of inflammatory pseudotumor, and if it's lymphocytic polyclonal infiltration you should be thinking about IgG4. So in summary, lymphocytic hypophysitis is a disease that usually affects postpartum or pregnant females. It can present with diplopia or vision loss -usually bitemporal hemianopsia. It causes an intrasellar mass with suprasellar extension that can look like pituitary hyperplasia or adenoma. Patients might have pan hypopituitarism or hyperprolactinemia. We should treat this with steroids and if a biopsy is done make sure it's not IgG4bytesting for IgG4in the serum and in the specimen.