[Peripheral precocious puberty: 46, XY complete gonadal dysgenesis]

Despite standard clinical definitions and availability of diagnostic tests for precocious puberty, an intensive and structured investigation is needed in order to diagnose the aetiology in particular cases. A 4-year-old, phenotypically female child was referred to paediatric endocrinology consultation for premature pubarche and thelarche. There was an acceleration of growth velocity with high levels of estradiol and testosterone, and prepubertal FSH and LH measurements. Investigation showed bilateral gonadoblastoma as the cause of the peripheral precocious puberty. Genetic studies revealed 46 XY karyotype with mutation c.89G> T (p.Arg30Ile) in exon 1 of the SRY gene, confirming the diagnosis of complete gonadal dysgenesis. Disorders of sexual differentiation must be considered in the approach and investigation of peripheral precocious puberty, especially in the presence of ovarian tumours, such as gonadoblastoma and dysgerminoma.