AbstractMixed gonadal dysgenesis (MGD) is a rare sex development disorder, diagnosed by mosaic karyotype of 45,X/46,XY (classical form) with the presence of Müllerian structures, unilateral testis and contralateral streak gonad. MGD expresses diverse phenotypes, from female phenotype with virilization or turner stigmata, to ambiguous genitalia or male phenotype. Early diagnosis is crucial for effective correction of height, sexual development and cancer prevention. The study reports on a case of a 25-year-old patient, reared as female, presenting a large abdominal mass later confirmed as a mixed germ cell tumor. Associated findings were primary amenorrhea, ambiguous genitalia, short statue, gender dysphoria and hyperlipidemia. The study is the first to report on hyperlipidemia in MGD.