Ectasia of the rete testis: Beware of this masquerader.

Cystic/tubular ectasia of the rete testis is a rare benign entity and must be differentiated from testicular neoplasm. We report a case of bilateral rete testis-associated epididymal cyst in patient with abdominal mass. Scrotal swelling clinically was interpreted as testicular neoplasm.

INTRODUCTION

Rete testis is an anastomosing network of delicate tubules located in the hilum of the testicle (mediastinum testis) that carries sperm from the seminiferous tubules to the vasa efferentia. Rete tubular ectasia is a disorder of the rete testis in which many benign cysts are present. It is a rare benign entity having a typical sonographic appearance of cluster of small anechoic structures in the confluence of the mediastinum testis. It is usually asymptomatic and discovered incidentally on ultrasound. The main significance of this condition is that it must be differentiated from testicular neoplasm. This problem surfaces as a diagnostic dilemma when this condition is incidentally detected on scrotal ultrasonogram (USG) in patients presenting with testicular/scrotal mass or pain. While almost all malignant testicular tumors are solid lesions, some, such as teratoma, may have cystic components.

CASE REPORT

A 32-year-old male presented with slowly progressive abdominal mass. There was associated bilateral painless scrotal swelling. No fever or constitutional symptoms were present. Clinical diagnosis of testicular tumor was made. CECT of the abdomen revealed multiple enlarged retroperitoneal nodes. No peritoneal thickening/enhancement, free fluid, or liver/splenic focal lesions were seen. USG revealed numerous small discrete anechoic cystic structures clustered together in the region of rete testis [Figure 1]. No solid component or calcification was seen. No flow was seen in these structures on color Doppler. The involvement was bilateral, and size and number of the cysts varied between the two sides. Bilateral large cystic lesions were seen involving bilateral epididymis suggestive of epididymal cysts [Figure 2]. Fine needle aspiration cytology of the retroperitoneal node (abdominal mass) revealed mycobacterium tuberculosis. Diagnosis of bilateral tubular ectasia of rete testes with large epididymal cyst was made. Epididymal or efferent duct obstruction leading to epididymal cyst and ectasia of rete testis was considered as an etiological factor. Tubercular retroperitoneal nodes were seen till aortic bifurcation and were not compressing the efferent duct/epididydmis, thus were considered not to be related to ectasia of the rete testis.

Figure 1

Sagittal sonogram of the left testis (a) and right testis (b) shows an ovoid cluster of small cystic elements (arrows) within the mediastinum testis, suggestive of tubular ectasia of the rete testis.

Figure 2

Sagittal sonogram of the left testis shows large septated cystic lesions involving the left epididymis suggestive of epidydmal cyst. Similar cyst was seen involving the right epididymis.

DISCUSSION

Ectasia of the rete testis is an acquired condition which can be associated with and occur as a result of mechanical compression of the epididymis or spermatic cord by surgical, traumatic, neoplastic or infectious processes and ischemic or hormonally induced atrophic alterations in epididymal tubules. Scrotal surgery or disorders associated with obstruction, such as vasectomy or epididymitis, may be associated with dilatation of the rete testis.[12] Spermatocele and epididymal cysts are also commonly associated with ectatic rete testis.[34] While a testicular tumor may compress the efferent ducts and cause ectasia, the solid mass should be distinct from the rete testis dilation. So an associated adjacent tumor must be ruled out. Ovoid cluster of anechoic cystic spaces that are located peripherally in the mediastinum testis, without a solid component within or adjacent to it, with no flow within the lesion on pulsed or color Doppler imaging and normal adjacent testicular parenchyma - these features are pathogonomic for cystic ectasia of the rete testis. Tubular ectasia of the rete testis is bilateral in approximately one-third of cases.[5] In our case bilateral involvement was seen.

In addition, the typical patient with ecstatic rete testis is older than patients with a testicular germ cell tumor. Median age of the patients found to have ectasia of the rete testis was 62 years.[2] The age of the patient, clinical presentation, and tumor marker status allow diagnosis of a tumor with fair certainty. In our case, the age of patient was less than previously reported cases and no associated testicular tumor was seen.

Cystic ectasia of the rete testis must be differentiated from other benign intratesticular lesions, notably cystic dysplasia and intratesticular varicocele.[6] Cystic dysplasia is similar sonographically and histologically, but it is a congenital lesion that occurs in children and is associated with ipsilateral renal or urogenital excretory duct malformations. Cystic ectasia can be differentiated from intratesticular varicocele on color Doppler ultrasound. Furthermore, cystic ectasia should be distinguished from the rare papillary adenocarcinoma of the rete testis, in which a solid mass in the rete testis should be evident. Based on clinical and sonographic criteria, the diagnosis of cystic ectasia of the rete testis can usually be made without histological confirmation. MRI is helpful in doubtful cases. Identifying this entity and its associated conditions obviates the need for biopsy or orchiectomy.