Background: Mixed gonadal dysgenesis (MGD) is a subtype of the disorders of sex development (DSD) associated with sex chromosome abnormalities characterized by abnormal external genitalia, short stature, and primary amenorrhea. This disease is generally diagnosed from the neonatal stage to early childhood, and by puberty at the latest. Cases that are phenotypically female or those with ambiguous genitalia experience a high risk of gonadal tumor formation. As tumor risk is known to increase with age, prophylactic bilateral gonadectomy is recommended following early diagnosis.
Case presentation: Here we report a case of an adult Japanese woman diagnosed with MGD during treatment for a giant pelvic tumor. The patient initially visited a gynecology clinic during puberty for primary amenorrhea, at which time an abnormality was found with the external genitalia. However, a diagnosis of MGD was not made at this time, resulting in the development of a malignant gonadal germ cell tumor in adulthood.
Conclusions: For early diagnosis of MGD and the prevention of gonadal tumor formation, it is essential that gynecologists fully understand MGD and other DSD.
Keywords: 45,X/46,XY mosaicism; Case report; Disorders of sex development; Gonadal tumor; Mixed gonadal dysgenesis; Primary amenorrhea.