Pituitary Gland - Hyperplasia







comment:
Focal hyperplasia is a frequent spontaneous as well as induced change and is seen more commonly in rats than in mice. The microscopic appearance is variable but consists primarily of a single cell type that blends into the adjacent parenchyma without compression ( Figure 1





Focal hyperplasia of the pars intermedia ( Figure 6


There is a morphologic continuum between hyperplasia and pituitary neoplasia, with compression of the adjacent parenchyma being a primary diagnostic feature of neoplasia. Immunohistochemistry for pituitary hormones can be used to determine cell type.
recommendation:
Focal hyperplasia should be diagnosed and given a severity grade whenever present, and the part of the pituitary involved should be specified in the diagnosis (e.g., Pituitary Gland, Pars distalis - Hyperplasia). Any remarkable features of hyperplasia may be described in the pathology narrative. Angiectasis within the hyperplastic lesion should not be diagnosed separately.references:
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Capen CC, DeLellis RA, Yarrington JT. 1991. Endocrine system. In: Handbook of Toxicologic Pathology (Haschek WM, Rousseaux CG, eds). Academic Press, New York, 697-705. Abstract: http://www.sciencedirect.com/science/book/9780123302151
Carlton WW, Gries CL. 1983. Cysts, pituitary; rat, mouse, and hamster. In: Endocrine System (Jones TC, Mohr U, Hunt RD, eds). Springer, New York, 161-163. Abstract: http://www.springer.com/medicine/pathology/book/978-3-642-96722-1
Greaves P. 2007. Histopathology of Preclinical Toxicity Studies: Interpretation and Relevance in Drug Safety Evaluation, 3rd ed. Academic Press, Amsterdam, 953. Abstract: http://www.sciencedirect.com/science/book/9780444527714
MacKenzie WF, Boorman GA. 1991. Pituitary gland. In: Pathology of the Fischer Rat: Reference and Atlas (Boorman G, Eustis S, Elwell M, Montgomery CA, MacKenzie W, eds). Academic Press, San Diego, 485-500. Abstract: http://www.ncbi.nlm.nih.gov/nlmcatalog/9002563
Mahler J, Elwell M. 1999. The pituitary gland. In: Pathology of the Mouse: Reference and Atlas (Maronpot RR, Boorman GA, Gaul BW, eds). Cache River Press, Vienna, IL, 491-508. Abstract: http://www.cacheriverpress.com/books/pathmouse.htm
Tucker MJ. 1998. The endocrine system. In: Target Organ Pathology (Turton J, Hoodon J, eds). Taylor and Francis, London, 311-334. Abstract: http://www.amazon.com/Target-Organ-Pathology-Basic-Text/dp/0748401571
Web page last updated on: August 08, 2014