WHO classification of uterine tumors

The World Health Organization (WHO) classification of tumors of the uterine corpus is a commonly used classification system for uterine tumors. It is part of the 5^th edition WHO classification of female genital tumors, published in 2020 ¹. 

Classification

Endometrial epithelial tumors and precursors

• precursor lesions

  • endometrial hyperplasia without atypia

  • endometrial atypical hyperplasia / endometrioid intraepithelial neoplasia

• endometrial carcinomas: most common of all uterine malignancies (>90%)

  • endometrioid carcinoma: most common histological subtype

  • serous carcinoma: ~10%

  • clear cell carcinoma: <10%

  • undifferentiated and dedifferentiated carcinomas: ~2%

  • mixed carcinoma: ~10%

  • other endometrial carcinomas: rare (includes mesonephric adenocarcinoma (~1%), mesonephric-like adenocarcinoma, squamous cell carcinoma (<5%), mucinous carcinoma) 

  • carcinosarcoma: previously known as a malignant mixed Müllerian tumor (~5% of all uterine malignancies)

Tumor-like lesions

• endometrial polyp

• endometrial metaplasia

• Arias-Stella reaction

Mesenchymal tumors of the uterus

• smooth muscle tumors

  • uterine leiomyoma

  • intravenous leiomyomatosis

  • smooth muscle tumor of uncertain malignant potential (STUMP)

  • metastasizing leiomyoma

  • uterine leiomyosarcoma

• endometrial stromal and related tumors

  • endometrial stromal nodule

  • low-grade endometrial stromal sarcoma

  • high-grade endometrial stromal sarcoma

  • undifferentiated uterine sarcoma

• miscellaneous mesenchymal tumors

  • uterine tumor resembling ovarian sex cord tumor

  • perivascular epithelioid cell tumor (PEComa)

  • inflammatory myofibroblastic tumor

  • other mesenchymal tumors of the uterus: rare (includes vascular tumors, lipomatous tumors, alveolar soft part sarcoma, solitary fibrous tumor, nerve sheath tumors, NTRK sarcomas, giant cell tumor)

Mixed epithelial and mesenchymal tumors

• adenomyoma

• atypical polypoid adenomyoma

• adenosarcoma of the uterus 

Miscellaneous tumors

• central primitive neuroectodermal tumor (PNET) / CNS embryonal tumor

• germ cell tumors

Related pathology

Tumors involving the uterus but classified elsewhere (i.e. not of the uterine corpus)​:

• gestational trophoblastic disease: including gestational choriocarcinoma

• uterine lymphoma: rare (primary or secondary)

• local invasion from other tumors:

  • bladder carcinoma

  • colorectal carcinoma

  • tubal carcinoma

  • vaginal carcinoma

  • cervical carcinoma

• metastases to the uterus: rare

See also

• WHO classification of tumors of the uterine cervix