Ovarian tumors

Ovarian tumors are relatively common and account for ~6% of female malignancies. This article focuses on the general classification of ovarian tumors. For specific tumor features, please refer to the relevant subarticles.

Pathology

Subtypes

Primary ovarian tumors

Surface epithelial-stromal ovarian tumors (60-70%):

• ovarian serous tumors
  • ovarian serous cystadenoma: ~60% of serous tumors  
  • ovarian borderline serous cystadenoma: ~15% of serous tumors
  • ovarian serous cystadenocarcinoma: ~25% of serous tumors; commonest malignant ovarian tumor
• ovarian mucinous tumors: ~20% of all ovarian tumors ¹¹
  • ovarian mucinous cystadenoma: ~80% of mucinous tumors
  • ovarian borderline mucinous cystadenoma: 10-15% of mucinous tumors
  • ovarian mucinous cystadenocarcinoma: 5-10% of mucinous tumors
• ovarian endometrioid tumor: 8-15% of all ovarian tumors
• clear cell ovarian carcinoma: ~5% of ovarian cancer
• Brenner tumor: ~2.5% of ovarian epithelial neoplasms
• squamous cell carcinoma of the ovary
• ovarian cystadenofibroma* / ovarian adenofibroma: can be serous, mucinous, endometrioid, clear cell or mixed
• ovarian cystadenocarcinofibroma: extremely rare
• ovarian fibrosarcoma
• undifferentiated carcinoma of the ovary: ~4% of all ovarian tumors

* sometimes classified as a separate category rather than under epithelial ⁷

Germ cell ovarian tumors (~20%):

• ovarian teratoma: the commonest primary benign tumor of the ovary
  • mature ovarian (cystic) teratoma
  • immature ovarian teratoma
  • specialized teratomas of the ovary
    • struma ovarii tumor
    • ovarian carcinoid tumors
• ovarian dysgerminoma
• ovarian yolk sac tumor: endodermal sinus tumor
• ovarian embryonal carcinoma
• ovarian choriocarcinoma: <1% of ovarian tumors
  • pure primary ovarian choriocarcinoma: extremely rare ²
• malignant mixed germ cell tumor of the ovary

Sex cord / stromal ovarian tumors (8-10%):

• ovarian fibrothecoma: ~5% of ovarian tumors
  • ovarian fibroma: ~4% of ovarian tumors
  • ovarian thecoma: ~1% of ovarian tumors
• sclerosing stromal tumor of the ovary: rare ⁹
• ovarian Sertoli-Leydig cell tumor - ovarian androblastoma: ~0.5% of ovarian tumors
• granulosa cell tumor of the ovary: commonest malignant sex cord tumor
  • juvenile granulosa cell tumor of the ovary
  • adult granulosa cell tumor of the ovary
• small cell carcinoma of the ovary ¹⁵

Mixed

These are uncommon:

• collision tumors of the ovary
• ovarian carcinosarcoma <1% 

Other

• ovarian lymphoma
  • primary ovarian lymphoma
  • secondary involvement of the ovary with lymphoma
• metastases to the ovary
  • Krukenberg tumor
  • other metastatic lesions to the ovary

Classification according to morphology

Predominantly cystic

• serous cystadenoma
• mucinous cystadenoma 
• mature cystic teratoma
• serous cystadenocarcinoma
• mucinous cystadenocarcinoma

Predominantly solid

• Brenner tumor
• thecoma
• fibroma
• endometroid granulosa cell tumors
• dysgerminoma
• endodermal sinus tumor (yolk sac tumor)
• metastatic

Serological tests

• CA-125 levels: elevated in most ovarian malignancies (~80% in general); some mucinous and germ cell tumors may not secrete this marker
• AFP levels: elevated particularly with immature ovarian teratomas (~50% of cases) and ovarian yolk sac tumors
• β HCG: in a small number of dysgerminomas
• human epididymis protein 4 (HE4): elevated in malignant ovarian diseases, being helpful to complement the Ca-125 in premenopausal women 

Risk factors

General risk factors include

• nulliparity
• early menopause 
• gonadal dysgenesis
• family history: contributes to 24% of cases of epithelial ovarian cancer¹⁴
  • BRCA1/BRCA2 mutations: particularly for serous types
  • Lynch syndrome-associated ovarian cancers most often have an endometrioid or serous type histology ¹⁴
• smoking: especially for mucinous adenocarcinoma
• previous history of breast, endometrial or colon cancer (Lynch II)
• certain ethnic groups

Protective factors

• oral contraceptives (OCP)
• breastfeeding (however this is controversial)

Risk assessment

• risk of malignancy index in ovarian tumors

Staging

The FIGO staging system is used for almost all of ovarian cancers: see ovarian cancer staging.