Testicular Sertoli cell tumour and potentially testicular Leydig cell tumour are features of syndrome.

syndrome is a rare paediatric autosomal dominant inherited disorder predisposing to various benign and malignant tumours. It is caused by a germline pathogenic variant in , and the second hit for tumour development is usually a missense hotspot pathogenic variant in the DICER1 ribonuclease IIIb domain. While predisposing variants account for about 60% of ovarian Sertoli-Leydig cell tumours, no -related testicular stromal tumours have been described. Here we report the first two cases of testicular stromal tumours in children carrying a germline pathogenic variant: a case of Sertoli cell tumour and a case of Leydig cell tumour diagnosed at 2 and 12 years of age, respectively. A somatic hotspot pathogenic variant was detected in the Sertoli cell tumour. This report extends the spectrum of -related tumours to include testicular Sertoli cell tumour and potentially testicular Leydig cell tumour. Diagnosis of a testicular Sertoli cell tumour should prompt genetic testing so that patients with a germline pathogenic variant can benefit from established surveillance guidelines. genetic evaluation may be considered for testicular Leydig cell tumour. Our findings suggest that miRNA dysregulation underlies the aetiology of some testicular stromal tumours.