[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [General pathology](https://durgical.com/en/general-pathology/) › [Female genital tract](https://durgical.com/en/general-pathology/areas/female-genital/) › Endometrioid, clear cell and Brenner tumours of the ovary # Endometrioid, clear cell and Brenner tumours of the ovary - Lesion Two ovarian cancers that grow out of endometriosis, and a mostly benign tumour made of cells that look like bladder lining. Updated Nov 12, 2026 ## Key points - Both endometrioid and clear cell carcinoma arise from endometriosis, often in an endometrioma; ARID1A loss is common to both. - Endometrioid: glands like endometrium, squamous morules; PTEN, CTNNB1, PIK3CA, KRAS and mismatch repair; often low grade with a good prognosis. - Synchronous endometrioid tumours of ovary and endometrium are often clonally related but behave well when both are low grade. - Clear cell: clear and hobnail cells in tubulocystic and papillary patterns; Napsin A and HNF1-beta; poor response to chemotherapy when advanced. - Brenner tumour: nests of transitional cells with grooved coffee-bean nuclei in dense fibrous stroma; usually benign, unilateral, often incidental. ## What it is Endometrioid and clear cell carcinomas of the ovary are the endometriosis-associated cancers. Endometrioid carcinoma resembles its endometrial namesake, shares mutations in PTEN, ARID1A, CTNNB1 and the mismatch repair genes, and may coexist with an independent-looking endometrial carcinoma. Clear cell carcinoma has glycogen-rich clear and hobnail cells, ARID1A loss and resistance to chemotherapy. Brenner tumours are usually small, benign, solid tumours of urothelial-like nests in fibrous stroma. ## Structure - Endometrioid: solid and cystic mass, back-to-back glands with columnar cells, squamous differentiation. - Clear cell: cells with abundant clear cytoplasm (glycogen) and hobnail nuclei, hyaline basement-membrane material in papillae. - Brenner: a firm white nodule; urothelial-type nests, sometimes with central mucinous cells; Walthard cell nests on the tube may be their origin. ## Step by step - Endometriosis on the ovary provides epithelium under chronic oxidative stress from repeated haemorrhage. - ARID1A, PIK3CA and other mutations accumulate in the endometriotic epithelium. - Atypical endometriosis develops, then invasive endometrioid or clear cell carcinoma. - Mismatch-repair defects, sporadic or from Lynch syndrome, contribute in a subset. ## Markers - PAX8 positive - ER and PR (endometrioid) - Napsin A and HNF1-beta (clear cell) - GATA3 and p63 (Brenner) ## Clinical notes - Often present at an earlier stage than high-grade serous carcinoma, as a pelvic mass in a woman with endometriosis. - Ovarian clear cell carcinoma is associated with hypercalcaemia and thromboembolism. - Patients with endometrioid or clear cell carcinoma are tested for mismatch-repair deficiency. ## Memory aid Endometriosis grows two daughters: one copies the endometrium, the other wears clear glass and hobnails. ## Test yourself Think of the answer, then tap the question to see it. ## Which two ovarian carcinomas arise from endometriosis? Endometrioid carcinoma and clear cell carcinoma. ## Which gene is commonly lost in both? ARID1A, a chromatin-remodelling tumour suppressor. ## What does a Brenner tumour look like under the microscope? Nests of urothelial-like (transitional) cells with grooved coffee-bean nuclei in a dense fibrous stroma. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/general-pathology/endometrioid-clear-cell-and-brenner-tumours-of-the-ovary/) [More Pathology questions →](https://durgical.com/en/practice/?f=pathology) ## Elsewhere in DurgiPedia - [Ovary: follicles, ovulation and corpus luteum](https://durgical.com/en/histology/ovary-follicles-ovulation-and-corpus-luteum/) ## Connections ## Related 7 - [Endometriosis and adenomyosis](https://durgical.com/en/general-pathology/endometriosis-and-adenomyosis/) - [Endometrioid endometrial carcinoma](https://durgical.com/en/general-pathology/endometrioid-endometrial-carcinoma/) - [Ovarian tumours: classification](https://durgical.com/en/general-pathology/ovarian-tumours-classification/) - [Mucinous ovarian tumours](https://durgical.com/en/general-pathology/mucinous-ovarian-tumours/) - [Urothelial tumours: morphology, grade and stage](https://durgical.com/en/general-pathology/urothelial-tumours-morphology-grade-and-stage/) - [Tumour suppressor genes: RB, TP53, APC, BRCA and the two-hit hypothesis](https://durgical.com/en/general-pathology/tumour-suppressor-genes-rb-tp53-apc-brca-and-the-two-hit-hypothesis/) - [Precancerous conditions: when chronic inflammation, metaplasia or hyperplasia raise the risk](https://durgical.com/en/general-pathology/precancerous-conditions-when-chronic-inflammation-metaplasia-or-hyperplasia-rais/) ## Related conditions 5 - [Ovarian cancer](https://durgical.com/en/conditions/ovarian-cancer/) - [Endometriosis](https://durgical.com/en/conditions/endometriosis/) - [Lynch syndrome (hereditary non-polyposis colorectal cancer)](https://durgical.com/en/conditions/lynch-syndrome/) - [Hypercalcaemia of malignancy](https://durgical.com/en/conditions/hypercalcaemia-of-malignancy/) - [Ovarian cyst](https://durgical.com/en/conditions/ovarian-cyst/) [← All of general pathology](https://durgical.com/en/general-pathology/) Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given. Sources: [Epithelial Ovarian Cancer](https://www.ncbi.nlm.nih.gov/books/NBK567760/) (StatPearls (NCBI Bookshelf), 2026); [Endometriosis](https://www.ncbi.nlm.nih.gov/books/NBK567777/) (StatPearls (NCBI Bookshelf), 2026). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/general-pathology/endometrioid-clear-cell-and-brenner-tumours-of-the-ovary/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/general-pathology/endometrioid-clear-cell-and-brenner-tumours-of-the-ovary/