Ambiguous genitalia in a newborn with 45,X/46,X,idic(Y) ovotesticular disorder of sex development.

Objective: To discuss a case of ovotesticular disorder of sex development (DSD) with ambiguous genitalia, isodicentric Y sex chromosome mosaicism, and unique histopathologic findings.

Methods: We report the clinical, laboratory, imaging, and operative findings, and we highlight the pertinent features of this case. Results of hormonal and genetic testing are reviewed, and histopathologic findings are illustrated.

Results: A term newborn had ambiguous genitalia and was found to have an uncommon 45,X/46,X,idic(Y) karyotype. This infant had a 2-cm phallic structure, a penoscrotal hypospadias, a gonad easily palpable in the right scrotum, and a second gonad palpable high in the left inguinal canal. On ultrasonography, both gonads appeared as normal testicles, and no müllerian structures were identified. Testosterone and dihydrotestosterone levels were normal for a male neonate. After assessment of the patient at 2 months of age because of an incarcerated left inguinal hernia, both gonads were removed and were found to have both testicular and ovarian tissues spread throughout, with a fallopian tube on the left and an incipient juvenile granulosa cell tumor on the right. He was then diagnosed with ovotesticular DSD and continued to be raised as a boy.

Conclusion: This male infant had undervirilization and an ovotesticular DSD. He had evidence of both ovarian and testicular tissues, in conjunction with apparent alterations in local müllerian inhibiting substance levels that allowed one fallopian tube to be preserved. The proportion of actively transcribed Y material in the chromosomes of patients with this karyotype may partially explain the variable phenotypes that can occur.