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21 results

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  • Clinically Non-Functioning Human Pituitary Adenomas

  • Sylvia L. Asa, Kalman Kovacs
  • Journal:
    Canadian Journal of Neurological Sciences / Volume 19 / Issue 2 / May 1992
    Published online by Cambridge University Press:
    18 September 2015, pp. 228-235
    • Article
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  • Clinically non-functioning pituitary adenomas are morphologically classified into two groups, those which have hormone immunoreactivity and ultrastructural features of known adenohypophysial cell types but are clinically silent, and those composed of cells that do not resemble nontumorous adenohypophysial cell types. Among the fomer are the silent somatotroph adenomas, silent corticotroph adenomas and silent gonadotroph adenomas; the latter include the silent type III adenomas, null cell adenomas and oncocytomas. We review their histological, immunohistochemical and ultrastructural features, the results of in situ hybridization to determine hormone synthesis by these tumors and data obtained from tissue culture characterizing their hormone release in vitro. Non-functioning adenomas represent a heterogeneous group. The discrepancies between morphology, immunoreactivity and lack of endocrine activity of silent adenomas are not clear. Oncocytomas are variants of null cell adenomas. We suggest that null cell adenomas and oncocytomas originate in uncommitted pluripotent precursor cells capable of undergoing multidirectional differentiation. The progenitor cells differentiate most frequently toward FSH / a-subunit producing cells; the mechanism of preferential differentiation is obscure.

  • 58 - Mechanisms of pituitary tumorigenesis

  • from Part 3.2 - Molecular pathology: cancers of the nervous system
    • By Shereen Ezzat, Department of Medicine, University of Toronto and the Princess Margaret Cancer Center, University Health Network, Toronto, Ontario, Canada, Sylvia L. Asa, Department of Pathology and Laboratory Medicine, University of Toronto, Department of Pathology, University Health Network, Toronto, Ontario, Canada
  • Edited by Edward P. Gelmann, Columbia University, New York, Charles L. Sawyers, Memorial Sloan-Kettering Cancer Center, New York, Frank J. Rauscher, III
  • Book:
    Molecular Oncology
    Published online:
    05 February 2015
    Print publication:
    19 December 2013, pp 652-668

  • Summary

    Introduction

    The pituitary, a small bean-shaped gland at the base of the brain, maintains multiple homeostatic functions, including metabolism, growth, and reproduction. Most pituitary tumors are adenomas that develop in the adenohypophysis, the epithelial anterior lobe composed of six cell types that secrete polypeptide hormones.

    Pituitary adenomas exhibit a wide range of hormonal and proliferative behaviors (1). They may be small, slowly growing and hormonally inactive, detected as radiographic “incidentalomas” or at post-mortem examination. When they produce hormones in excess, they cause mood disorders, sexual dysfunction, infertility, obesity and disfigurement, hypertension, diabetes mellitus, and accelerated heart disease. Untreated, hormone excess syndromes can be associated with diminished survival.

    Some pituitary adenomas grow rapidly, producing symptoms of an intra-cranial mass, loss of normal anterior pituitary hormone production, and visual ield disturbances due to stretching of the overlying optic chiasm.hey can invade downward into paranasal sinuses, laterally into the cavernous sinuses (thereby disrupting co-ordinated eye movement) and upwards into the brain.hey can cause death by invasion of brain.

    Early studies using X-chromosome inactivation proved that these adenomas are monoclonal neoplasms (2–5). Polyclonal results were attributed to contamination by normal tissue; the small adenomas associated with Cushing’s syndrome are particularly subject to this phenomenon (4,5).

Endocrine Pathology
  • Edited by Ozgur Mete, Sylvia L. Asa
  • Published online:
    13 April 2017
    Print publication:
    01 January 2000
  • A much-needed comprehensive resource, Endocrine Pathology covers clinical, radiologic, biochemical, molecular, cytogenetic, immunologic and histopathologic aspects of endocrine disorders, including the full spectrum of both neoplastic and non-neoplastic lesions. The first section of the book provides an overview of the clinical presentations of endocrine diseases, while the second section reviews the wide variety of investigative techniques used in their diagnosis. The third and largest section provides a comprehensive tissue- and organ-based approach to the diagnosis of endocrine disorders, including morphologic, genetic and proteomic features with clinicopathologic correlations. All chapters are richly illustrated with numerous color images, tables and algorithms, and the book is packaged with a password, giving the user online access to all text and images. Written and edited by the world's leading experts, this comprehensive and up-to-date book is the definitive resource on endocrine pathology for all pathologists, endocrinologists and researchers.

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