This article reports a case of a 7-year-old girl with Turner syndrome, treated with growth hormone (GH), who developed ovarian dysgerminoma. The patient karyotype was mosaic for chromosome Xq deletion: 46,X,del(X)(q22)/45,X. No Y chromosome sequences were present. Molecular studies revealed the presence of a driving mutation in exon 17 of the KIT gene in the neoplastic tissue, as well as Sonic-hedgehog (SHH) pathway activation at the protein level. The patient responded well to chemotherapy and remained in complete remission. This is the first case of dysgerminoma in a Turner syndrome patient with such oncogenic pathway.

Germ cell tumors (GCTs) are a heterogenous group of neoplasms in children and young adults, in which serum tumor markers have been demonstrated to be highly sensitive diagnostic and monitoring tools. The known "old" serum biomarkers, alpha-fetoprotein (AFP), human choriogonadotropin (β-hCG) and lactate dehydrogenase (LDH), have some limitations in sensitivity and specificity. MIRNAs from the miR-371~373 (chromosomal locus 19q13.41) and miR-302/367 (4q25) clusters are universally over-expressed in malignant GCT tissue samples. The levels of miRNAs from these clusters are elevated in the serum. They seem to be highly sensitive and specific in malignant GCTs diagnosis and disease assessment during treatment and follow-up. The aim of our review was to present the role of serum tumor markers in the clinical staging, treatment monitoring and follow-up of pediatric patients with GCTs and show new possibilities. The serum levels of miRNAs seem to be a new, promising essential tool in the clinical management of GCTs.