Ovarian tumors, or ovarian neoplasms, aretumors in theovary.^[1] Not all areovarian cancer.^[1] They consist of mainly solid tissue, whileovarian cysts contain fluid.^[2]

In 2020, theWorld Health Organization (WHO) divided ovarian tumors as 90% epithelial, 3% germ cell, and 2% sex cord-stromal types.^[3]

Serous tumors

Class	Type	Subtypes	Epidemiology	Comments	Micrograph	Image
Serous tumor of the ovary[4]	Benign serous tumors[5]	Serous cystadenoma of the ovary
		Serous surface papilloma
		Serous adenofibroma
	Serous borderline tumor of the ovary	Serous borderline tumor, micropapillary variant
	Malignant serous tumors carcinoma	Low grade serous carcinoma of the ovary (LGSC)[6]	Rare, 2-5% of ovarian cancers, 5-10% of serous ovarian cancers[6]	May occur following a serous borderline tumor.[6] 80% diagnosed at advanced stage[6] Better survival rate than HGSC.[7]
		High-grade serous carcinoma of the ovary (HGSC)		Distinct from LGSC[6] 80% diagnosed at advanced stage[6]

Mucinous tumors

Class	Type		Subtypes	Epidemiology	Comments	Micrograph	Image
Mucinous tumors of the ovary	Benign mucinous tumors	Mucinous cystadenoma and adenofibroma of the ovary
	Borderline mucinous tumor	Mucinous borderline tumor
	Malignant mucinous tumor	Mucinous carcinoma of the ovary

Endometrioid tumors

Clear cell tumors

Germ cell tumors

Type	Subtype	Relative incidence[8]	Percent malignant[8]	Comments	Micrograph	Image
Germ cell tumor	Matureteratoma of the ovary[9]	20% of all ovarian tumors[9]	Mostly benign, rarely become cancerous[9]	Cystic, with elements of all 3germ layers (endoderm,mesoderm andectoderm).[10]
	Immature teratoma of the ovary[11]	2.5%	100%	Ateratoma that containsanaplastic immature elements, and is often synonymous withmalignant teratoma.[12]
	Dysgerminoma of ovary[13]	1% of all ovarian cancers[13]
	Yolk sac tumor[14]	20% of cancerous ovarian germ cell tumors[14]
	Embryonal carcinoma[15]
	Non-gestational choriocarcinoma[16]
	Mixed germ cell tumor[17]

Sex cord-stromal tumor

Sex cord-stromal tumor can be purely stromal, purely sex cord, or mixed sex-cord subtypes.^[18]

Type	Subtype	Relative incidence[8]	Percent malignant[8]	Comments	Micrograph	Image
Sex cord-stromal tumor: pure stromal tumors, pure sex cord tumors and mixed sex cord-stromal tumors	Ovarian fibroma	1.5%	0%	Spindle-shaped fibroblastic cells and abundant collagen.[19]
	Adultgranulosa cell tumor	1%	Almost 100%	Small, bland, cuboidal to polygonal cells in various patterns.[20]
	Other sex cord-stromal tumors	1%		Others include mainlyjuvenile granulosa cell tumor,thecoma andsclerosing stromal tumor[8]
	Sex cord-stromal tumor NOS	The number of people who have this type of tumor, and the cause of it, is not known.[18]	A few may be cancerous, with a 92% 5-year survival rate.[18]	Also known asneoplasms of uncertain behaviour of female genital organs and sex cord-gonadal stroll tumor, it is a tumor without clearly defined features of a particular tumor.[18] They may be solid or a mixture of solid and cystic.[18]

Surface epithelial-stromal tumor

Type	Subtype	Relative incidence[8]	Percent malignant[8]	Comments	Micrograph	Image
Surface epithelial-stromal tumor	Serous tumor	25%	18.5%	Benign serous tumors of the right ovarian cyst are thinwalled unilocular cysts that are lined by ciliated pseudostratified cuboidal or columnar epithelium.[21]
	Mucinous tumor	15%	8.8%	Benign mucinous tumors of the ovary consist of simple, nonstratified columnar epithelium with basally-located hyperchromatic nuclei and resemble gastric foveolar epithelium.[21]
	Endometrioid tumor	1%	Almost 100%	Tubular glands, resembling endometrium.[22]
	Other surface-epithelial tumors	1.5%		Others include mainly malignant mixedmullerian tumor,Brenner tumor and mixed epithelial tumor.[8]

Mixed tumors contain elements of more than one of the above classes of tumor histology.

See also

• List of female genital tumors

References

• Ovarian cancer