45,X/46,XY Mosaicism with Male Phenotype: Case Report.

Mixed gonadal dysgenesis is the most common chromosomal abnormality with ambiguous genitalia, defined as a 45,X/46,XY mosaicism. It can present with a normal male phenotype, ambiguous genitalia, or features of Turner syndrome. A 14-year-old patient was referred to the genetics clinic due to hypospadia, cryptorchidism, and aortic coarctation. During the physical examination, short stature, webbed neck, and Blashko lines on his back were noted. He had a previous karyotype reported as normal. However, due to an inadequate evolution and a low resolution on the previous test, a higher resolution karyotype was performed, identifying a mosaicism 45,X/46,XY. A multidisciplinary board examined the case, and follow-up with tumor markers was carried out to evaluate the presence of gonadoblastoma, one of the main complications in these patients. Treatment should be transdisciplinary and focused on the particular characteristics of each case. Other treatment alternatives include corrective surgery and hormonal therapy.