Clinical History
A 36 years old man presented with a painless mass in the left scrotal space. The physical examination found a normal right testicle and two smaller masses in the left hemiscrotum.
Imaging Findings
US examination was performed with a 7.5 MHz probe demonstrating a right testicle and epididymis of normal size (long axis: 43 mm) and echotexture. The left hemiscrotum contained two round structures,
homogenously echogenic and well delimitated, identical to the normal right testis so were thought to be two small left testicles. The upper one was the smallest (long axis: 15 mm.). An echogenic band
connecting the two left masses was seen and was thought to be the left epididymis. MR was performed on a Signa 1.5T (General Electric). T1 and T2 weighted images were obtained in the sagittal, axial
and coronal planes. The MR showed two round masses in the left hemiscrotum with homogenous signal intensity, intermediate on T1 and high on T2, similar to that of the right testis. Each left testicle
was surrounded by the tunica albuginea which appear as a thin layer of low signal intensity on both T1 and T2. The common left epididymis showed a similar or slightly less signal than that of normal
testicular tissue. A diagnosis of poliorchidism was made and no further diagnostic evaluation or treatment was deemed necessary.
Discussion
Polyorchidism is a rare congenital anomaly resulting in supernumerary testicles, most often seen in young males. Frequently is asymptomatic, but also pain and scrotal mass palpation are common
findings. The supernumerary testicle is generally located into the scrotum, althoght the inguinal canal, peritoneum or retropeitoneum are not uncommon locations. 60% of cases are left side located
while bilateral duplications are rare.Embriologically each testicle develops from the urogenital ridge, a thickening along the medial aspect of the mesonephros. As the testis descends the more
cephalad ducts and tubules degenerate while new ones develop caudally. The exact explanation of the polyorchidism mecanism is still unknown, although several theories and related classifications have
been proposed.They talk about anomalous appropriations cells, longitudinal or transverse division, and duplication of the urogenital ridge, either through some local accident or by the development of
peritoneal bands. No cromosomal anomalies have been identified. The longitudinal duplication implies a division along the cranial-caudal axis, while the transverse one along the medial-lateral plane,
although intermediate stages are also possible. Three types are the results from these divisions: Type I. Longitudinal division: the extra testis lacks an epididymis and vas deferensType II.
Incomplete transverse division: the supernumerary testis is linked to the regular one by a common epididymis with a common vas deferens. Most common. Type III. Complete transverse division: the
supernumerary testis has its own epididymis, vas deferens and vessels. Rare. The most common is the type II, like this case report, where the testis are connected by a common epididymis leading to a
single spermatic cord. The complete transverse division of the testicle, epididymis and spermatic cord is extremely rare (type III). The presence of an accessory testis may be associated with various
anomalies, most commonly maldescent testis (either of the supernumerary or the ipsilateral normal one) and inguinal hernias. Others abnormalities like varicocele, testicular torsion, infertility,
epididimytis and neoplasm are rare. None of these associations were present in this case. In high resolution US supernumerary testis appear with a normal echo pattern, smooth margins, unequal in size
and usually smaller than the normal testis. Heterogeneus echogenicity of the testes, however, may be suggestive of underlying inflammation or malignancy and warrants attention and aggressive
management. Accurate assessment of polyorchidism is possible with US studies, although MR improves the evaluation of the epididymis and rule out focal intratesticular lesions. The supernumerary
testes have the same MR imaging characteristics as normal testes: intermediate signal in T1-weighted images and high signal intensity on T2 weighted images, with each testis surrounded by a
continuous band of low signal intensity on both T1 and T2 weighted images that represents the tunica albuginea. In the past biopsy or surgery has been proposed. Actually US and MR examination allows
a reliable diagnosis of this benign entity, rendering surgery unnecessary. So recognition of uncomplicated duplicated testis obviates surgical exploration and routine sonographic evaluations are
sufficient follow up. In unconclusive US studies MR imaging can be used to asses the diagnosis.
Differential Diagnosis List
