Whether benign or malignant, functional or organic, fluid or solid, ovarian masses are the most common gynecological tumors, with benign tumors and functional cysts greatly predominating. The annual incidence of ovarian neoplasms is estimated at 2.6 cases per 100,000 girls and they are very rarely malignant, representing only 1% of all cancers in children and adolescents. The variety and complexity of the symptoms of these masses pose many diagnostic difficulties and pelvic imaging is of unquestionable value -  in particular pelvic ultrasonography, which is the key diagnostic investigation.

New surgical techniques have been developed, including laparoscopy, which are generally reserved for the treatment of small persistent benign tumors to remove the cyst and preserve the underlying ovary.

Only surgery and histopathological analysis allow precise identification of the exact nature of a complex tumor. Ovarian masses in fact cover a wide range of pathologies, from more or less secretory tumors and benign but complex anomalies to highly aggressive and invasive tumors.

Generally, recognition of the precise histological type of the neoplasm goes beyond mere histopathological classification; prognosis and treatment depend on it. The work of Scully, who identified numerous categories of tumor, has led to an international classification recognized by the World Health Organization (WHO).

Review of Ovarian Embryology
The gonad appears in the first month of embryonic life as a localized thickening of the antero-internal aspect of the mesonephros, called the genital ridge, which is covered by the coelomic epithelium. At 6 weeks, the primordial germ cells penetrate the genital ridge and the cells of the coelomic epithelium proliferate to form the primitive sex cords which will surround the primordial germ cells and form the undifferentiated gonad. At 7 weeks, the gonad is undifferentiated and has dual potential. There are three essential stages in ovarian differentiation because Y and above all SRY are absent: the chromosomal stage where two Xs are present, the gonadal stage with ovarian orientation under the influence of gonadal differentiation factors, and a later hormonal stage with estrogen secretion. Ovarian differentiation begins at 10 weeks with the development of the primordial follicles in the cortex, while maturation ends at puberty.