Presence of more than two testicles in the same individual.
It is a rare anomaly with approximately 200 reported cases. The most frequent situation is triorchidism. With four testicles, less than a dozen cases have been observed (Uğuz et al. 2017). There are two cases with pentaorchidism, one diagnosed during surgical exploration without histological verification and another diagnosed by magnetic resonance imaging (Myers et al. 2017).
Age at diagnosis varied from birth to 75 years (Nistal et al. 1990).
No predilection of laterality.
Treatment depends on the location of the testicle, the anatomy of the pathways, and the histology of the testicle (Piro et al. 2017). In general, orchiectomy can be recommended in all the atrophic testes located outside the scrotum. Regular self-examination, clinical follow-up every 6 months, and annual ultrasound are recommended in the scrotal testes and in those who have been able to descend into the scrotum, trying to solve two problems, preserving fertility and early detection of a tumor.
In 5.4–6.4% tumors develop, mostly in undescended testes. The tumors include both sarcomas (rhabdomyosarcomas) and germ cell tumors (teratomas, seminomas, choriocarcinomas) (Noroozian et al. 2017).
The macroscopic observation of duplicate testicles has been the basis of different classifications from embryological base (Leung 1988) to those based on reproductive potential (Singer et al. 1992; Bergholz et al. 2007). Duplication probably occurs between weeks 4 and 6 of gestation. It would be produced by any of the following mechanisms: (a) Duplication of the genital ridge. The longitudinal division of the genital ridge and the mesonephric ducts would produce two testicles with their own excretory system capable of producing sperm. (b) Longitudinal division of the genital ridge. The resulting testicle located medially lacks an excretory pathway and atrophies. (c) High-transversal division of the genital ridge. The two testicles can have their own epididymis or share it. In any case, there is only one common vas deferens. (d) Low-transversal division of the genital ridge. The testicle located caudally lacks excretory pathways and atrophies.
The duplicated testicle in 50% of the cases shows lesions of spermatogenesis such as Sertoli cell-only, hypospermatogenesis, or maturation arrest. In some cases, lesions of spermatogenesis are primary and in others they have been related to the abnormal situation of the testicles or to the absence of communication of the testicle with the spermatic pathways.
Differential diagnosis includes most of the entities that produce scrotal or spermatic cord swelling from cysts and hydrocele to ectopias such as aberrant epididymis, adrenal cortex ectopia, crossed testicular ectopy, splenogonadal fusion, and tumors of the epididymis and spermatic cord. Like hydrocele and cysts and tumors of the epididymis, the differential diagnosis begins with high-resolution ultrasound, magnetic resonance in some cases, and surgical exploration. The findings will be confirmed by a histological study.