Sex-Cord Stromal Tumors

Sex-cord stromal tumors derive from coelomic epithelium or mesenchymal cells of the embryonic gonads (Young and Scully 2002a). Eight percent of all ovarian neoplasms account for this tumor type, with granulosa cell tumors, fibromas, thecomas, and Sertoli-Leydig cell tumors comprising the majority of these tumors. The 2014 revised WHO classification comprises pure stromal tumors, pure sex-cord tumors, and mixed sex-cord stromal tumors (Horta and Cunha 2015). Granulosa cell tumors are considered as low-­grade malignant tumors. Sertoli-Leydig cell and steroid tumors may be malignant depending on the degree of differentiation (Young and Scully 2002a). Sex-cord stromal tumors affect all age groups but are commonly encountered in periand postmenopausal women (Tanaka et al. 2004). Their clinical and differential diagnostic importance is based upon their hormone activity. Granulosa cell tumors may typically produce estrogens, but a minority may be hyperandrogenic. Sertoli-Leydig cell tumors and steroid cell tumors are androgen-producing tumors. The majority of sex-cord stromal tumors are confined to the ovary at the time of diagnosis (Outwater et al. 1998).

Granulosa Cell Tumors

Granulosa cell tumors are classified as neoplasm of a low malignant potential. The juvenile and the adult subtype differ in several important aspects. Adult granulosa cell tumors account for 1–2% of all ovarian tumors and for 95% of all granulosa cell tumors (Young and Scully 2002a). FOXL2 gene mutation is seen in the vast majority and is diagnostic of the adult tumor type (Kottarathil et al. 2013). Granulosa cell tumors are the most common ovarian tumors presenting with hyperestrogenism. The rare juvenile granulosa cell tumors are hormonally active in 80% and occur typically before the age of 30 years. The majority is found in prepubertal girls who present with the signs of precocious pseudopuberty with development of breasts and pubic and axillary hair. An association with Ollier’s disease (enchondromatosis) and Maffucci’s syndrome (enchondromatosis and hemangiomatosis) has been reported in some cases (Young and Scully 2002a).

Adult granulosa cell tumors occur after the age of 30 years and have their peak incidence in the perimenopausal age (median 51 years) (Young and Scully 2002a; Kottarathil et al. 2013). Estrogen expression may become clinically manifest as abnormal uterine bleeding and endometrial hyperplasia. Endometrial cancer is associated with these tumors in 3–22% of cases (Outwater et al. 1998). Peutz-Jeghers syndrome and Potter’s syndrome are also linked with granulosa cell tumors (Pennington and Wsisher 2012). Both types of granulosa cell tumors are typical unilateral­ ovarian tumors that vary considerably in size and show an average diameter of approximately 12 cm (Young and Scully 2002a). Unlike epithelial ovarian cancer, they are diagnosed in stage I in 71% of patients and in late stages (III and IV) in 19% (Kottarathil et al. 2013). Recurrence rates reach 25%, and recurrence tends to occur late at 4–5 years but may be seen even many years after the initial therapy (Young and Scully 2002a; Kottarathil et al. 2013). Relapse is typically confined to the pelvis and abdomen. However, distant metastases to the bone, supraclavicular lymph nodes, liver, and lungs have been reported (Kottarathil et al. 2013).

Imaging Findings

Granulosa cell tumors present typically unilateral, well-delineated often large masses. Irrespective of their distinct clinical features, both the juvenile and adult tumor type can display a broad spectrum of imaging features from entirely cystic to completely solid ovarian lesions (Fig. 26) (Jung et al. 2002).

Granulosa cell tumors may display homogenous contrast enhancement and intermediate to high SI on T2-weighted images. They may also manifest as a solid and cystic neoplasm, and cysts may contain hemorrhagic fluid. Papillary projections are not found and calcifications are rare (Horta and Cunha 2015). The adult type of granulosa cell tumors manifests mostly as a predominantly spongelike cystic multilocular tumor with blood clots and solid tissue (Kim 2002). In hormone-­active tumors, the endometrial cavity may be widened due to hyperplasia or endometrial cancer (Kottarathil et al. 2013; Kim 2002).