Uterus - Hyperplasia, Atypical

Image of hyperplasia, atypical in the uterus from a female Wistar Han rat in a chronic study
Uterus, Endometrium - Hyperplasia, Atypical in a female Wistar Han rat from a chronic study. The glandular epithelium projects into the glandular lumen (arrow), forming multiple thickened infoldings and projections.
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Image of hyperplasia, atypical in the uterus from a female Wistar Han rat in a chronic study
Uterus, Endometrium - Hyperplasia, Atypical in a female Wistar Han rat from a chronic study (higher magnification of Figure 1). There are multiple infoldings and projections of the endometrium into the uterine lumen.
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Image of hyperplasia, atypical in the uterus from a female Wistar Han rat in a chronic study
Uterus, Endometrium - Hyperplasia, Atypical in a female Wistar Han rat from a chronic study. The epithelium lining the uterine lumen projects into the lumen in irregular papillary fronds.
Figure 3 of 5
Image of hyperplasia, atypical in the uterus from a female Wistar Han rat in a chronic study
Uterus, Endometrium - Hyperplasia, Atypical in a female Wistar Han rat from a chronic study (higher magnification of Figure 3). The epithelial cells are irregularly arranged and exhibit cellular pleomorphism.
Figure 4 of 5
Image of hyperplasia, atypical in the uterus from a female Harlan Sprague-Dawley rat in a chronic study
Uterus - Hyperplasia, Atypical in a female Harlan Sprague-Dawley rat from a chronic study. There is atypical hyperplasia of both surface and glandular epithelium.
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comment:

Atypical hyperplasia of the endometrium is more commonly seen in longitudinal sections of uteri in NTP studies because its most frequent location is in the proximal uterine horns near the bifurcation of the uterine body. This lesion can affect both glandular ( Figure 1image opens in a pop-up window , Figure 2image opens in a pop-up window , and Figure 5image opens in a pop-up window ) and uterine surface epithelium ( Figure 3image opens in a pop-up window , Figure 4image opens in a pop-up window , and Figure 5image opens in a pop-up window ). This lesion is typically characterized by clusters of enlarged glands separated by minimal amounts of stroma, though single glands can be affected. The affected glands are lined by a disorganized epithelium that may be up to six cell layers in thickness ( Figure 1image opens in a pop-up window , Figure 2image opens in a pop-up window , and Figure 5image opens in a pop-up window ). The epithelial cells of atypical hyperplasia often display loss of nuclear polarization, karyomegaly, mitosis, and cellular pleomorphism ( Figure 4image opens in a pop-up window ). The thickened epithelium frequently projects into the glandular lumen, forming multiple thickened infoldings and projections ( Figure 1image opens in a pop-up window , Figure 2image opens in a pop-up window , and Figure 5image opens in a pop-up window ). The papillary type of atypical hyperplasia affects the surface epithelium ( Figure 3image opens in a pop-up window and Figure 4image opens in a pop-up window ) and consists of numerous small branching projections of epithelium extending into the uterine lumen, occasionally on small fibrovascular stalks. In some cases, both the glands and the surface epithelium can be affected concurrently ( Figure 5image opens in a pop-up window ). Atypical hyperplasia is differentiated from adenomas by the absence of compression and the fact that these lesions do not form a distinct mass.

recommendation:

Uterus - Hyperplasia, Atypical should be diagnosed and graded whenever present. The location of the lesion, in glands or in the epithelium lining the uterine lumen, should be described in the pathology narrative.

references:

National Toxicology Program. 2014. NTP TR-587. Toxicology Studies of Tetrabromobisphenol A (CAS No. 79-94-7) in F344/NTac Rats and B6C3F1/N Mice and Toxicology and Carcinogenesis Studies of Tetrabromobisphenol A in Wistar Han [Crl:WI(Han)] Rats and B6C3F1 Mice (Gavage Studies). NTP, Research Triangle Park, NC.
Abstract: http://ntp.niehs.nih.gov/go/41452