Non-Epithelial Ovarian Cancers

Germ cell ovarian cancer arises from the reproductive cells of the ovaries, and is rare.
Stromal cell ovarian cancer, which arises from connective tissue cells, is very rare.
Small cell carcinoma (SCCO) of the ovary is an extremely rare ovarian cancer, and it is not certain whether the cells in SCCO are from ovarian epithelial cells, stromal cells or germ cells.

Ovarian Germ Cell Tumors

  • Immature teratomas
  • Dysgerminoma
  • Yolk sac tumors

Germ cell tumors begin in the reproductive cells (egg cells) of the ovary. Benign variants of these tumors, such as dermoid cysts, are fairly common.  Malignant ovarian germ cell are rare, accounting for approximately 5 percent of ovarian cancer cases. They can occur in women of any age, but are more common in young women or adolescents. As a result, strategies to preserve fertility are important in the treatment of these cancers.

These tumors may present with symptoms similar to other ovarian tumors, including abdominal bloating or pain.  Unlike EOC, however, these cancers are often diagnosed at early stages, and as a result may be curable with surgical resection. 

There are three types of germ cell cancers:  immature teratomas, dysgerminomas, and yolk sac tumors. 

Immature Teratomas

Immature teratomas are a type of malignant ovarian germ cell cancer that is distinguished from benign mature teratomas (also called dermoids or dermoid cysts) based on the presence of poorly-differentiated (immature) cells. Malignant immature teratomas are 100 times less common than benign mature teratomas. 


Dysgerminoma, is the most common type of malignant germ cell tumor, and often affects women in their teens or twenties.  These cancers are also treated with surgery, sometimes in combination with chemotherapy or possibly radiation in advanced stage cases.  

Yolk Sac Tumors

Yolk sac tumors, also known as endodermal sinus tumors, account for about 15% of germ cell tumors. Yolk sac tumors are typically diagnosed prior to age 40—median age at diagnosis is 18-19–with about 40% of diagnoses occurring prior to puberty.  These cancers tend to grow rapidly and metastasize quickly, making treatment more challenging.

Ovarian Stromal Tumors

  • Granulosa Cell Tumor
  • Sertoli-Leydig Cell Tumor

Malignant ovarian stromal tumors are rare and represent approximately 1.2% of all ovarian cancers.  These tumors may arise from supporting stromal cells or from hormone-producing cells, called sex-cord cells, or may comprise a mix of these cell types.  Because sex-cord stromal cells of the ovary produce hormones, tumors arising from these cells may cause symptoms associated with increased hormone production.   Tumors that produce estrogen may cause early puberty in young girls, or menstrual changes in reproductive-aged women, while older women may develop vaginal bleeding after menopause. Tumors producing androgen hormones, such as testosterone, may cause excess hair growth, called hirsutism, deepening of the voice, or enlargement of the clitoris.   These tumors may also cause symptoms associated with the presence of a pelvic mass, such as abdominal pain or bloating.  

Granulosa Cell Tumors

Granulosa cell tumors are the most common type of malignant sex-cord stromal tumors, comprising 2-5% of all ovarian cancers.  These tumors often produce hormones, and symptoms associated with hormone overproduction.  Two types of granulosa cell tumors have been described, adult-type and juvenile-type.  The majority (95%) of these tumors occur in older women, with a median age of 54.  The juvenile subtype is rare and typically develops before puberty.  Granulosa cell tumors are often diagnosed in early stages and managed surgically.  Advanced stage disease may be treated with chemotherapy.

Sertoli-Leydig Tumors

Sertoli cells and Leydig cells are other types of stromal cells in the ovary.  Cancers developing from the stroma may include a mix of these cell types.  Sertoli-Leydig cell tumors are rare, but like granulosa cell tumors, they may produce hormones, including androgens.  Management of Sertoli-Leydig tumors usually includes surgery and chemotherapy.  

Rare Ovarian Cancer Subtypes

Some rare ovarian cancers may appear to include a mix of cell types.  

Ovarian Carcinosarcoma

Malignant mixed Mullerian tumors of the ovary, also called carcinosarcomas, include cells that have features of stroma and cells that have features of epithelium.  These cancers are now thought to be a rare and aggressive variant of an epithelial carcinoma, comprising 1-4% of ovarian cancer cases.  Carcinosarcomas are most often diagnosed in postmenopausal women. 

Small Cell Carcinoma of the Ovary

Small cell carcinoma of the ovary (SCCO) is a very rare, highly malignant tumor, with a median age at diagnosis of 23 years. SCCO accounts for 0.1 percent of ovarian cancer cases. It is not certain whether the cells in SCCO are from ovarian epithelial cells, sex-cord stromal cells or germ cells.

The subtypes of SCCO include pulmonary, neuro-endocrine and hypercalcemic. 

Small cell neuro-endocrine tumors of the ovary are extremely rare, with only 35 known cases reported as of 2011. 

The symptoms are the same as other types of ovarian cancer. If you’re interested in viewing a webinar about small cell carcinoma of the ovary, hypercalcemic type, you can watch it here.