Polyorchidism

Polyorchidism, also known as supernumerary testes, refers to the presence of more than two testes and is a very rare congenital anomaly. The supernumerary testis can be usually located inside the scrotum (75% of the patients) or less commonly in the inguinal canal, the retroperitoneum, or the abdominal cavity ^1-3.

Epidemiology

Polyorchidism is rare, with only 140 cases reported up to 2013.

Clinical presentation

Polyorchidism is asymptomatic in the majority of patients. Some patients may present with scrotal pain, scrotal swelling, hydrocele, varicocele, epididymitis, infertility, testicular malignancy, or testicular torsion ². Testicular torsion is the most commonly encountered complication of polyorchidism ³.

Clinical examination usually reveals that the testes have normally descended into the scrotum. However, a nodule can be palpable inside the affected hemiscrotum. This nodule is easily differentiated from the normal testes but may raise concern for malignancy.

As polyorchidism usually causes no symptoms, it is often found incidentally during self-examination or surgery for inguinal hernia, testicular tumor, or torsion ¹. Polyorchidism is commonly associated with inguinal hernia (24%), undescended testis (22%) and microlithiasis ¹.

Pathology

There are several types of this condition with triorchidism being the most common. In this type, there are three testes with the supernumerary being situated on the left in 65% of the cases. In 4.3% of patients with polyorchidism, there is bilateral involvement with four testes.

Etiology

Polyorchidism is a developmental anomaly with abnormal division of the genital ridge. The genital ridge can be longitudinally or transversely divided or duplicated before the 8^th week of fetal development. The Wolffian duct may be duplicated as well.

Classification

Polyorchidism is classified into two major types, A and B, based on the venous drainage of the testis (see Figure 1).

• type A polyorchidism: the supernumerary testis is drained by a separate ductus deferens and consequently has reproductive potential

  • type A3 represents the most frequent subtype and represents 90% of all cases of polyorchidism

• type B polyorchidism: the supernumerary testis is not drained by a ductus deferens and thus has no reproductive potential ¹

Radiographic features

Ultrasound

Scrotal ultrasonography demonstrates the normal echogenicity of the testes. The supernumerary testis/testes can be seen as a solid nodule isoechoic to the testes and has the same echotexture. This nodule is usually located lower than the normal testes and is smaller. Hydrocele is present in 9% of patients ¹. 

Color Doppler or power Doppler ultrasonography reveals normal blood flow in the supernumerary testis, with the same characteristics as in the two normal testes ⁴.

MRI

In case ultrasonography does not provide a conclusive diagnosis, MRI can be very helpful. The supernumerary testis has the same signal intensity as the normal testes ⁴:

• T1: intermediate signal intensity

• T2: high signal intensity

Treatment and prognosis

The management of patients with polyorchidism is under debate. Removal of a supernumerary or ectopic testis with orchiectomy is recommended by some due to the high risk of malignancy (4-7%). Cryptorchidism is considered to be the greatest risk factor for malignancy in patients presenting with polyorchidism.

Alternative management includes preservation of an incidentally found supernumerary testis and long-term follow-up. Treatment can be based on whether or not the supernumerary testis possesses a ductus deferens ^2-4.   

History and etymology

The term "polyorchidism" derives from the Greek root "πολυ-" (poly-) meaning plenty and the word "όρχις" (orchis) meaning testis and was first used by Arbuthnot​ Lane in 1895 to report a case discovered at surgery.

Differential diagnosis

Possible differential considerations include:

• scrotal hernia

• bilobed testis

• crossed testicular ectopia

• testicular tumor