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15 February 2012 - Case of the Week #233
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(1) The second half of the Lymphoma and plasma cell neoplasms chapter (T/NK cell disorders, Hodgkin's lymphoma, post-transplant, other) was recently updated, based on a review by Dragos C. Luca, M.D., Children's Hospitals & Clinics of Minnesota. The balance of this chapter was updated in early 2011.
(2) Visit our new Forensic Pathology chapter, currently under development. We also continually add to our Drugs of Interest to Pathologists chapter.
Case of the Week #233
A 62 year old woman had a 7 x 4.5 x 4.0 cm adnexal mass, and underwent a TAH BSO.
What is your diagnosis?
Endometrioid borderline tumor, also known as endometrioid tumor of low malignant potential
Ovarian endometrioid tumors closely resemble their more common counterparts in the uterus. Some cases are associated with endometriosis, either in the same ovary or elsewhere. Ovarian endometrioid borderline tumors have low malignant potential, and are composed of atypical or outright malignant-appearing endometrioid glands in a dense fibrous stroma. The absence of stromal invasion differentiates the borderline tumors from endometrioid adenocarcinoma.
Three histologic patterns of endometrioid borderline tumor have been described: adenofibromatous, villoglandular and combination adenofibromatous and villoglandular.1 This case demonstrates the adenofibromatous pattern, with prominent squamous morules and metaplasia in the glands. Some of the glands with squamous metaplasia have central necrosis or keratin formation.
Oliva et. al. found β-catenin mutations in seven of eight endometrioid borderline tumors; one case had both a β-catenin and a PTEN mutation. KRAS mutations were not found, and all eight tumors were MSI stable. This supports the idea that β-catenin mutations are an early event in the development of low grade endometrioid tumors, and that endometrioid borderline tumors may evolve into low grade endometrioid adenocarcinomas. Strong nuclear immunohistochemical staining for β-catenin was seen in 10%-60% of the glandular component of the tumors, and in most of the squamous morules.2
This tumor has an excellent prognosis, with only rare recurrences or metastases. Endometrioid borderline tumors are most often unilateral, but a few patients treated with unilateral salpingo-oophorectomy later developed endometrioid adenocarcinoma in the contralateral ovary.1
1. Tavassoli: Pathology and Genetics of Tumours of the Breast and Female Genital Organs. IARC Press, 2003.
2. Oliva E, Sarrio D, Brachtel EF, Sanchez-Estevez C, Soslow RA, Moreno-Bueno G, Palacios J: High frequency of beta-catenin mutations in borderline endometrioid tumours of the ovary, J Pathol 2006, 208:708.
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