Endometrial intraepithelial neoplasia

Endometrial Intraepithelial Neoplasia, (EIN) is a premalignant lesion of the uterine lining that predisposes to endometrioid endometrial adenocarcinoma. It is composed of a collection of abnormal endometrial cells, arising from the glands that line the uterus, which have a tendency, over time to progress to the most common form of uterine cancer - endometrial adenocarcinoma, endometrioid type. =History=EIN lesions have been discovered by a combination of molecular, histologic, and clinical outcome studies beginning in the 1990s which provide a multifaceted characterization of this disease. They are a subset of a larger mixed group of lesions previously called "endometrial hyperplasia Mutter GL, Duska L, Crum CP. Endometrial Intraepithelial Neoplasia. In: Crum CP, Lee K, editors. Diagnostic Gynecologic and Obstetric Pathology. Philadelphia, PA: Saunders, 2005: 493-518.] Silverberg SG, Mutter GL, Kurman RJ, Kubik-Huch RA, Nogales F, Tavassoli FA. Tumors of the uterine corpus: epithelial tumors and related lesions. In: Tavassoli FA, Stratton MR, editors. WHO Classification of Tumors: Pathology and Genetics of Tumors of the Breast and Female Genital Organs. Lyon, France: IARC Press, 2003: 221-232.] " The EIN diagnostic schema is intended to replace the previous "endometrial hyperplasia" classification as defined by the World Health Organization in 1994, which have been separated into benign (benign endometrial hyperplasia) and premalignant (EIN) classes in accordance with their behavior and clinical management.
EIN should not be confused with an unrelated entity, serous intraepithelial carcinoma ("serous EIC"), which is an early stage of a different tumor type known as papillary serous adenocarcinoma that also occurs in the same location within the uterus.=Clinical Aspects =The average age at time of EIN diagnosis is approximately 52 years, compared to approximately 61 years for carcinoma. The timeframe and likelihood of EIN progression to cancer, however, is not constant amongst all women. Some cases of EIN are first detected as residual premalignant disease in women who already have carcinoma, whereas other EIN lesions disappear entirely and never lead to cancer. For this reason, treatment benefits and risks must be individualized for each patient under the guidance of an experienced physician.
Risk factors for development of EIN and the endometrioid type of endometrial carcinoma include exposure to estrogens without opposing progestins, obesity, diabetes, and rare hereditary conditions such as hereditary nonpolyposis colorectal cancer. Protective factors include use of combined oral contraceptive pills (low dose estrogen and progestin), and prior use of a contraceptive intrauterine device.

=Biology=EIN lesions demonstrate all of the behaviors and characteristics of a premalignant, or precancerous, lesion.
Precancer Features of EIN (Table I). The cells of an EIN lesion are genetically different than normal and malignant tissues, and have a distinctive appearance under the light microscope. EIN cells are already neoplastic, demonstrating a monoclonal growth pattern and clonally distributed mutations. Progression of EIN to carcinoma, effectively a conversion from a benign neoplasm to a malignant neoplasm, is accomplished through acquisition of additional mutations and accompanied by a change in behavior characterized by the ability to invade local tissues and metastasize to regional and distant sites.
Table I: Precancer Characteristics of EIN=References=External Links=

Patient Resources

[http://www.cancer.org American Cancer Society]

[http://www.wcn.org Women's Cancer Network] an educational and research organization

[http://www.gog.org Gynecologic Oncology Group] an NIH-Funded research group that runs clinical trials

[http://oncolink.upenn.edu OncoLink] an excellent educational site from the U. of Pennsylvania

Find a board certified specialist at the [http://www.sgo.org Society of Gynecologic Oncologists]
Pathology

[http://www.uscap.org US and Canadian Academy of Pathology]

[http://www.endometrium.org www.endometrium.org] a pathology site focusing on endometrial disease
PTEN Gene

[http://www.cancerindex.org/geneweb/PTEN.htm Cancer Genetics Web] PTEN entry

[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=search&db=PubMed&term=PTEN+endometr* PTEN and the Endometrium at PubMed]

[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=gene&cmd=Retrieve&dopt=full_report&list_uids=5728 Entrez Gene] PTEN entry
Other

[http://www.cancer.gov/cancer_information/ CancerNet] an NIH database with clinical and scientific information

[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed PubMed] a search engine and database for Medical Literature