WHO classification of uterine tumors

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

Classification

Endometrial epithelial tumours 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 tumour (~5% of all uterine malignancies)

Tumour-like lesions

• endometrial polyp

• endometrial metaplasia

• Arias-Stella reaction

Mesenchymal tumours of the uterus

• smooth muscle tumours

  • uterine leiomyoma

  • intravenous leiomyomatosis

  • smooth muscle tumour of uncertain malignant potential (STUMP)

  • metastasising leiomyoma

  • uterine leiomyosarcoma

• endometrial stromal and related tumours

  • endometrial stromal nodule

  • low-grade endometrial stromal sarcoma

  • high-grade endometrial stromal sarcoma

  • undifferentiated uterine sarcoma

• miscellaneous mesenchymal tumours

  • uterine tumour resembling ovarian sex cord tumour

  • perivascular epithelioid cell tumour (PEComa)

  • inflammatory myofibroblastic tumour

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

Mixed epithelial and mesenchymal tumours

• adenomyoma

• atypical polypoid adenomyoma

• adenosarcoma of the uterus 

Miscellaneous tumours

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

• germ cell tumours

Related pathology

Tumours 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 tumours:

  • bladder carcinoma

  • colorectal carcinoma

  • tubal carcinoma

  • vaginal carcinoma

  • cervical carcinoma

• metastases to the uterus: rare

See also

• WHO classification of tumours of the uterine cervix