Pars intermedia of the human pituitary revisited: Morphologic aspects and frequency of hyperplasia of POMC-peptide immunoreactive cells
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The human pituitary has no distinct pars intermedia (PI). Instead, the proopiomelanocortin (POMC) producing, adrenocorticotropin (ACTH)- and β-endorphin-immunoreactive PI cells are incorporated within the pars anterior, thereby participating in the formation of the pars distalis. Two hundred fifty autopsy pituitaries (156 males, 94 females) have been studied by histology and immunohistochemistry to determine the frequency of clinically non-functioning ACTH- and β-endorphin immunoreactive (POMC) cell hyperplasia/adenoma probably attributable to PI-derived cells. Such hyperplasia occurred in 29% of men and 14% of women; 80% of the male and 77% of the female subjects were over 50 yr of age. In two of the women, POMC cell adenoma was present as well. Except for hypothyroidism, none of the cases with POMC cell hyperplasia had endocrine disorder. No obvious correlation was evident between POMC cell hyperplasia/adenoma and clinical presentation. Hyperplasia of PI-derived POMC cells may be suspected by virtue of differential intraglandular localization of these cells. Except for cases of glucocorticoid treatment, leading to Crooke’s hyalinization of ACTH cells, but not affecting PI cells, no conclusive separation of various POMC-producing subsets is possible at present. The PI-derived cells probably give rise to silent “corticotroph” adenoma subtype 1 and subtype 2.
Key WordsHuman pituitary pars intermedia POMC cells hyperplasia adenoma
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- 1.Hanström B. Gross anatomy of the hypophysis in mammals. In: Harris GW, Donovan BT, eds. The Pituitary Gland, vol. 1, London: Butterworths, 1966: 1–57.Google Scholar
- 2.Holmes RL, Ball JN. The pituitary gland. A Comparative Account. Cambridge: Cambridge University Press, 1974.Google Scholar
- 3.Russfield AB. Adenohypophysis. In: Bloodworth JMB Jr, ed. Endocrine Pathology. Baltimore: Williams and Wilkins, 1968; 75–116.Google Scholar
- 7.McNicol AM, Teasdale GM, Beastall GH. A study of corticotroph adenomas in Cushing’s disease: no evidence of intermediate lobe origin. Clin Endocrinol 24:715–722, 1986.Google Scholar
- 10.Horvath E, Kovacs K. The adenohypophysis. In: Kovacs K, Asa SL, eds. Functional Endocrine Pathology, vol. 1, Boston: Blackwell Scientific, 1991: 245–281.Google Scholar
- 16.Rasmussen AT, Nelson AA: Pars intermedia basophil adenoma of the hypophysis. Am J Pathol 14:297–310, 1938.Google Scholar
- 25.Henville KL, Vinson GP. The effect of α-MSH peptides on adrenal steroidogenesis by human adrenal cellsin vitro. J Endocr 111: (Suppl) 91, 1986.Google Scholar
- 26.Coates PJ, McNicol AM, Doniach I, Rees LH. Increased production of α-melanocyte-stimulating hormone in the pituitary gland of patients with untreated Addison’s disease. Clin Endocrinol 29:421–426, 1988.Google Scholar
- 32.Braithwaite SS, Clasen RA, D’Angelo CM. Silent corticotroph adenoma: case report and literature review. Endocr Prac 3:297–301, 1997.Google Scholar
- 33.Oka H, Kameya T, Sasano H, Aiba M, Kovacs K, Horvath E, et al. Pituitary choristoma composed of corticotrophs and adrenocortical cells in the sella turcica. Case report. Virchows Arch Pathol Anat 427:613–617, 1996.Google Scholar