LYMPHOCYTIC HYPOPHYSITIS - LIGHT AND ELECTRON-MICROSCOPIC FINDINGS AND CORRELATION TO CLINICAL-APPEARANCE

Light and electron microscopic findings of six cases of lymphocytic hy pophysitis of a collective of 2500 surgical specimens are presented. F ive cases were obtained by surgery, one case was obtained from autopsy . Light microscopy revealed an infiltration of mature lymphocytes and plasma cells in the interstitium, partly in the acini, as well as in t he posterior lobe and the capsule. The structure of the remaining ante rior lobe was normal. The final stage of lymphocytic hypophysitis is f ibrosis, which was seen in all cases to varying degrees. The infiltrat e consisted mainly of T-lymphocytes, being positive for CK 45 RO and C D 43. Immunocytochemical staining revealed different proportions of re sidual adenohypophyseal cells, Mainly prolactin reactive cells were ob served as were growth hormone reactive cells. By electron microscopy s ame ruptured acini and damaged adenohypophyseal cells could be seen. F ew pituitary cells contained enlarged lysosomal bodies or oncocytic ch anges. Inflammation causing enlargement of the pituitary leads to pati ents often being operated under the preoperative diagnosis of a tumor of the sellar region. It is important to identify this special type of hypophysitis, as a different course of treatment is required.