Subclinical adenomas in postmortem pituitaries: classification and correlations to clinical data

Objectives: The aim of this study was to examine pituitary adenomas in a large collective of postmortem pituitaries by use of modern technologies of immunostaining, to classify the adenomas according to the current WHO classification and to analyze possible associations to available clinical data.

Methods: In this study pituitaries of 3048 cases obtained from autopsy series of the years 1991 to 2004 were examined. Detailed immunohistochemical staining followed for prolactin (PRL), adrenocorticotropic hormone (ACTH), follicle-stimulating hormone (FSH), luteinizing hormone (βLH), α-subunit, S-100 protein and MIB-1. The available clinical data were analysed.

Results: A total of 334 pituitary adenomas were found in 316 pituitaries. 132 sparsely granulated prolactinomas (39.5%), 75 null cell adenomas (22.5%) and 31 oncocytomas were diagnosed. 46 ACTH cell adenomas (13.8%, 27 densely granulated, 19 sparsely granulated) and one adenoma composed of Crooke's cells were detected. 22 gonadotroph cell adenomas (6.6%), seven GH cell adenomas (4 sparsely granulated, 3 densely granulated), one mixed GH cell-PRL cell adenoma, two TSH cell adenomas, five plurihormonal adenoma type I, four plurihormonal adenoma type II and two α-subunit-only adenomas were seen. Six adenomas remained unclassified because the tissue was not contained in all sections for immunohistochemistry. 17 pituitaries included multiple tumours. The overall tumour size ranged from 0.1 to 20mm in diameter. 138 tumours had a tumour size of 1mm or less, only three tumours were macroadenomas corresponding to a size of more than 10mm. The evaluation of available clinical data showed 99 cases of hypertension, 65 cases of diabetes mellitus, six patients with hyper- and four with hypothyroidisms. No symptoms of adenohypophyseal hormone hypersecretion were reported. The statistical evaluation showed no significant correlations to clinical data.

Conclusion: Adenomas in postmortem pituitaries differ from those in surgical series in regard to adenoma types, functional properties and biological behaviour.