The anterior pituitary lobe in patients with cystic craniopharyngiomas: three cases of associated lymphocytic hypophysitis.

Specimens of the anterior pituitary lobe were investigated histologically in 28 craniopharyngioma patients operated on trans-sphenoidally. The pituitary glands in 3 patients revealed lymphocytic invasion giving a histological appearance typical of lymphocytic hypophysitis (incidence: 11%). At follow-up examination all three patients with associated lymphocytic hypophysitis had complete pituitary insufficiency, whereas only 36% of the craniopharyngioma patients without associated lymphocytic hypophysitis were in this poor postoperative endocrine state. The phenomenon of associated lymphocytic hypophysitis in craniopharyngioma patients has not been reported so far. This might be due to the fact that investigators have failed to systematically examine the anterior pituitary lobe in craniopharyngioma patients. The 60 cases of lymphocytic hypophysitis reported in the literature occurred, for the most part, in women during late pregnancy or shortly after delivery. An auto-immune origin is assumed in this type of inflammation. In contrast to this pathophysiological mechanism, we assume a local induction of inflammation resulting from the craniopharyngioma cyst in our 3 patients.