Research question: Is there potential for the detection of neuroblastoma malignancy in testicular tissue extracted for fertility preservation for prepubertal boys at the time of tissue freezing?

Design: This is a case report.

Results: A boy was diagnosed with primary localized left adrenal neuroblastoma, with complete resection of the tumour. During 6 months' surveillance, he developed a relapse in the left para-renal region with progression of molecular and chromosomal features into undifferentiated neuroblastoma. Before highly gonadotoxic treatment, testicular biopsy for fertility preservation was taken, from a clinically normal testis. Histopathological examination of the testicular biopsy revealed metastatic neuroblastoma.

Conclusions: Metastatic neuroblastoma detected histologically in a clinically normal testis highlights the importance of routine histological examination at the time of testicular cryopreservation. The histological evaluation of gonadal tissue for potential malignant contamination before freezing should be mandatory, regardless of the malignancy diagnosis. Advances in sensitive molecular detection and in-vitro maturation are critically required to decrease future risk of disease recurrence in both solid and haematological malignancies.