Pituitary Changes in Ataxia-Telangiectasia Syndrome: An Immunocytochemical, In Situ Hybridization, and DNA Cytometric Study of Three Cases.

Ataxia-telangiectasia (AT) syndrome (cerebellar ataxia, oculocutaneous telangiectasias, immunodeficiency, susceptibility to infections, and neoplasia) is associated with cyto- and nucleomegaly in several organ systems. Our aim was to determine (1) whether such cellular abnormalities in the pituitary selectively involve specific cell types, and (2) the proliferation and DNA ploidy status of such cells. Three AT autopsy pituitaries were studied by histology, immunohistochemistry (pituitary hormones, MIB-1, p53 protein), in situ hybridization (pituitary hormones), and Feulgen stain image analysis for ploidy. Results indicated that, in adenohypophyses the scattered pleomorphic, bizarre nuclei were mainly those of somatotrophs and corticotrophs, growth hormone (GH), or adrenocorticotropic hormone (ACm) immunoreactive and expressing the GH or ACTH gene, respectively. Cyto- and nucleomegaly were less frequent in other secretory cells but were also noted in pituicytes of the posterior lobe. Affected cells were immunonegative for MIB-1 and for p53 protein. Image morphometric DNA analysis showed the bizarre cells to be aneuploid with complex histogram patterns, including many nuclei with DNA contents >8 n. No adenomas were found. We conclude that in AT adenohypophyseal cells with cyto- and nucleomegaly, as well as pleomorphism, synthesize and store adenohypophyseal hormones, mainly GH or ACTH. They and affected pituicytes are nonproliferative and are aneuploid.