Embryological basis of polyorchidism including classification, reproductive potential, and risk of malignancy: A review

Polyorchidism, a congenital malformation characterized by supernumerary testes (SNTs), is usually revealed incidentally during ultrasound or open scrotal surgery. In the approximately 200 cases so far published in the literature, the left side is affected more often than the right. Despite the rarity of this anomaly, a surgeon must have basic knowledge of its embryological basis and classifications to implement proper treatment and avoid overlooking it, since the consequences could harm the patient. This review summarizes previous classifications. It can be assumed that determining the risk of malignancy, and the level of reproductive potential based on location, vascularization, ductus deferens drainage, and environmental factors (e.g., temperature) affecting the SNTs, indicates the best approach to management. Therefore, we have created a new classification based on previous ones, addressing the aforementioned issues, which will guide the clinician to select the most appropriate treatment.