Histological Assessment of Gonads in DSD: Relevance for Clinical Management.

Malignant gonadal germ cell tumors, referred to as germ cell cancers (GCC), occur with increased frequency in individuals who have specific types of differences (disorders) of sex development (DSD). Recent population-based studies have identified new environmental and genetic risk factors that have led to a 'genvironment' hypothesis, which may potentially be helpful in risk assessment in DSD-related GCC. In DSD, the malignancy risk is highly heterogeneous, but recent studies allow now to discriminate between high- and low-risk conditions. Gonadal biopsy is in some cases the best procedure of choice to assess the risk, and with the availability of immunohistochemical biomarkers [OCT3/4 (POU5F1), TSPY, SOX9, FOXL2 and KITLG (SCF)], a reliable classification of GCC and its precursors can be made. The opportunities in the field of virtual diagnostic pathology will be presented, having possibilities for rare diseases in general and DSD specifically. It is expected that the International DSD Registry will stimulate international collaborations, facilitating better diagnostic procedures as well as research.