Pituitary Gland - Cyst
comment:Pituitary cysts in the pars distalis are frequent incidental findings in rats more than a year old and in mice. Most are remnants of the craniopharyngeal (Rathke's) pouch and are distinct from Rathke's cleft dilation that is localized between the pars distalis and pars intermedia. Pituitary cysts may be single or multiple, may contain eosinophilic proteinaceous or mucoproteinaceous fluid, are often lined by ciliated cuboidal to columnar cells, and typically do not compress surrounding parenchyma. The ciliated epithelial lining may be incomplete. The epithelial lining distinguishes them from angiectasis and/or enlarged vascular sinuses and from cystic degeneration, where irregular edges are lined by degenerating secretory cells. Occasionally, the adenohypophysis contains small follicle-like structures that are incidental and should not be diagnosed as cysts. The presence of multiple epithelium-lined cysts in the pars nervosa (arrows, Figure 4 and Figure 5 ) suggests an origin from the infundibular lumen. A dilated Rathke’s cleft (asterisks, Figure 4 and Figure 5 ) may also be present.
The majority of the literature dealing with pituitary cysts makes reference to a craniopharyngeal origin and further indicates that Rathke's pouch is part of the craniopharyngeal structure. Consequently, cysts of Rathke's pouch and craniopharyngeal cysts are synonymous. Determination of the origin of specific cysts may be difficult.
recommendation:While attempting to distinguish the origin of pituitary cysts is not critical, these cysts should be diagnosed whenever present, and the part of the pituitary in which the cysts occur should be indicated in the diagnosis (e.g., Pituitary Gland, Pars nervosa - Cyst). If there are multiple cysts, the modifier "multiple" should be included in the diagnosis. Since chronic studies may incorporate in utero exposure, developmental alterations potentially related to treatment could influence the ultimate presence and appearance of pituitary cysts. A severity grade would be appropriate if there is a potential treatment-related effect on the occurrence or severity of this change.
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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
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Web page last updated on: August 08, 2014