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Advances in Anatomic Pathology:
Pathology and the Internet

Endometrial Intraepithelial Neoplasia

Wheeler, Darren T MD

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Author Information

From the Armed Forces Institute of Pathology, Gynecologic and Breast Pathology Department, Washington, DC (, and (

The incidence of endometrial cancer in women is estimated to be 1% to 2% for the general population. The incidence of dysfunctional uterine bleeding is significantly higher, although the exact incidence is unknown. It is therefore not surprising that endometrial biopsies and curettings typically make up a significant component of general surgical pathology practice. Surprisingly, there is little content concerning the pathology of the endometrium on the Internet. Although most of the web sites concerning endometrial hyperplasia and cancer are aimed at patient education, there is one site focused on the surgical pathology of premalignant lesions of the endometrium:

Dr. George Mutter, a pathologist at the Brigham and Women’s Hospital, Harvard Medical School, has focused much of his research on premalignant lesions of the endometrium. In order to educate pathologists on his proposed terminology of endometrial intraepithelial neoplasia (EIN) for these lesions, he has created a web site discussing the entity of EIN and its comparison with the classical World Health Organization (WHO) hyperplasia system. The main page of the web site has links to upcoming endometrial pathology courses and information concerning PTEN, a tumor suppressor gene whose loss of function has been the most common genetic lesion seen in endometrioid adenocarcinoma. In addition, there is a link to “EIN Central.” It is here that the criteria for diagnosing EIN are discussed, using 3 modules of instruction with an interactive quiz following completion of the modules. The quiz consists of 15 H&E cases, and the user diagnoses each case as “EIN” or “non-EIN.”

For those who prefer using the standard WHO hyperplasia terminology for the diagnosis of premalignant lesions of the endometrium, the most useful area of the site is the “data repository.” Under this link, there is an “EIN Diagnosis Library,” which features 50 endometria diagnosed by the WHO system, with their EIN diagnosis comparison. Each case is linked to 5 to 8 high-quality H&E jpeg images for review. For each case, the patient age, a brief discussion of the H&E histology, and outcome with variable follow-up are provided. This latter feature sets these cases apart from a typical online atlas, providing valuable insight into which lesions progressed to carcinoma. In addition, there is a second archive of endometrial pathology images, representing a group of cases with accompanying specialized studies including clonal analysis, K-ras mutation studies, and computerized morphometric analysis. These 93 cases show the subjective WHO diagnosis by a panel of expert pathologists with the comparison to the EIN diagnosis. Each case is linked to 2 representative H&E jpeg images. Last, there are links to EIN course notes and syllabi and recommendations for how to handle the more ambiguous cases.

Whether or not you’re a proponent of the EIN system, this web site is a great way to sharpen your skills in the diagnosis of premalignant lesions of the endometrium and their benign mimics. Because evaluation of the gland-to-stroma ratio is critical in both the EIN and WHO hyperplasia systems, the tutorials provided within the site are beneficial to those using either system. In addition, the ability to look at over 100 endometria, many of which have clinical follow-up, is an invaluable resource.

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© 2004 Lippincott Williams & Wilkins, Inc.


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