Hyperthecosis, or ovarian hyperthecosis, is hyperplasia of the theca interna of the ovary. Hyperthecosis occurs when an area of luteinization occurs along with stromal hyperplasia. The luteinized cells produce androgens, which may lead to hirsutism and virilization (or masculinization) in affected women.
The term hyperthecosis refers to the presence of nests of luteinized theca cells in the ovarian stroma due to differentiation of the ovarian interstitial cells into steroidogenically active luteinized stromal cells. These nests or islands of luteinized theca cells are scattered throughout the stroma of the ovary, rather than being confined to areas around cystic follicles as in polycystic ovary syndrome (PCOS). These luteinized theca cells result in greater production of androgens.
Seen as a severe form of PCOS, the clinical features of hyperthecosis are similar to those of PCOS. Women with hyperthecosis often have more markedly elevated testosterone, more hirsutism, and are much more likely to be virilized. While elevated androgens in postmenopausal women is rare, hyperthecosis can present in both premenopausal or postmenopausal women. Women with hyperthecosis may or may not have always had underlying PCOS.