An endometrioma (OMA) is the localization of endometriosis in ovary, and it most often develops as a cyst. The pathogenesis of OMA is still an open question and controversial; a cystic hemorrhagic corpus luteum may be a prerequisite, occurring as a transition to an endometriotic cyst. Inversion and progressive invagination of the ovarian cortex after the accumulation of menstrual debris derived from bleeding of superficial endometriotic implants, located on the ovarian surface and adherent to the peritoneum, is another hypothesis. Gene studies show that WNT4 and FN1 are predisposing genes for OMA development. A role of environmental toxicants in the development of OMA is also under investigation; dioxins and dioxin-like compounds (DLCs), interacting with steroid receptors, are possible factors. Even if women with endometriosis have a 1.5 times greater lifetime risk to develop an ovarian carcinoma, an OMA is not to be considered a preneoplastic lesion.
The clinical management of OMAs is complex and should be individualized. Ultrasounds and magnetic resonance imaging (MRI) are sensitive but not specific for diagnosis. Treatment is influenced by patient age, desire for pregnancy, pain severity, cyst dimensions and characteristics (unilateral/bilateral), coexistence of deep endometriosis, previous gynecological or obstetrical history and previous surgery. Laparoscopic surgery is considered the treatment of choice in cases of infertile patients with a large OMA or pain, and in patients not responding to medical therapy. It should be performed with proper techniques by trained surgeons to decrease the damage to the remaining ovarian tissue, and to maintain the ovarian reserve after surgery. A medical hormonal and nonhormonal treatment is used for asymptomatic and/or pain-associated OMA (progestins, estroprogestins and antiinflammatory drugs). Considering the relative high recurrence rate after surgery, a medical treatment should be offered.