Cystic Ectasia of the Rete Testis: Clinical and Radiographic Features

0022-5347/02/1684-1436/0 THE JOURNAL OF UROLOGY® Copyright © 2002 by AMERICAN UROLOGICAL ASSOCIATION, INC.®

Vol. 168, 1436 –1438, October 2002 Printed in U.S.A.

DOI: 10.1097/01.ju.0000026687.18857.54

CYSTIC ECTASIA OF THE RETE TESTIS: CLINICAL AND RADIOGRAPHIC FEATURES JASON K. BURRUS, MARK E. LOCKHART, PHILLIP J. KENNEY

AND

PETER N. KOLETTIS*

From the Division of Urology, Department of Radiology, University of Alabama at Birmingham, Birmingham, Alabama

ABSTRACT

Purpose: Cystic ectasia of the rete testis is a rare condition that may be incidentally noted on scrotal ultrasonography. This benign condition has a typical appearance of a collection of small anechoic structures in the confluence of the mediastinum testis. The main significance of this condition is that it must be differentiated from testicular neoplasm. We reviewed the experience with this condition at our institution. Materials and Methods: A retrospective review was performed to identify all sonograms showing ectatic rete testis performed from 1998 through February 2002. A departmental database was used to identify all scrotal sonograms from this period showing ectasia of the rete testis and clinical correlation was done. These examinations were then reviewed by a single radiologist. Results: We identified 13 cases in the last 4 years. Ultrasound was most commonly performed for a testicular or scrotal mass, or pain. Median patient age was 65 years. All except 1 patient had an underlying condition, including vasectomy, epididymal cyst/spermatocele or inguinal hernia repair, that could cause epididymal or efferent duct obstruction. No patient had a solid testicular mass. Conclusions: Based on clinical and sonographic criteria the diagnosis of cystic ectasia of the rete testis can be made without histological confirmation. Identifying this entity and its associated conditions avoids the need for biopsy or orchiectomy. KEY WORDS: rete testis; testis; ultrasonography; dilatation, pathological

Ultrasonography is the imaging technique of choice for evaluating scrotal abnormalities. Virtually all solid testis masses are malignant and necessitate orchiectomy. Differentiating benign conditions from malignant testis tumors is critical because it can spare the patient inguinal exploration and biopsy or orchiectomy. Previous scrotal surgery may further complicate the ultrasound interpretation.1 Dilatation or ectasia of the rete testis, that is the anastomosing spaces where the tubuli recti enter the mediastinum testis, is a benign condition that may be visualized on scrotal sonography. This condition may be noted incidentally on scrotal ultrasound performed for a scrotal mass or pain. Scrotal surgery or disorders associated with obstruction, such as vasectomy, spermatocele or epididymitis, may be associated with dilatation of the rete testis.2 If the clinician is unaware of the existence of this entity, it can be misinterpreted as testicular malignancy. We reviewed our experience with this condition and describe its clinical and radiographic features.

longitudinal images were obtained, and color and spectral Doppler ultrasound was performed. In all except 1 patient spectral Doppler ultrasound was done as part of the examination. The typical appearance of the rete testis is an echogenic structure communicating from the mediastinum testis to the epididymal head. The rete is usually located at the posterolateral aspect of the testis. Occasionally the rete may be anechoic with numerous tiny round or tubular structures, indicating tubular ectasia of the rete testis. The cysts may track along the mediastinum and be quite variable in size and number. However, to our knowledge there are no standardized criteria for the size or number of these cysts for diagnosing cystic rete testis in the radiological literature. Demographic and clinical information on these patients was then analyzed. Particularly careful attention was paid to identify other urological and scrotal abnormalities that may be associated with cystic ectasia of the rete testis.

MATERIALS AND METHODS

RESULTS

We obtained institutional review board approval for our study. We searched a departmental database to identify all patients diagnosed with cystic dilatation of the rete testis at our institution in the last 41⁄2 years. These examinations were then reviewed by a single radiologist (M. E. L.). Ultrasound of the scrotum consisted of imaging the testes, epididymides, paratesticular structures and spermatic cords in systematic fashion. The examination was performed with the patient supine and the scrotum elevated by a sheet wrapped around the patient pelvis. A 7 to 15 MHz. transducer was used but occasionally a curved transducer was necessary due to extreme scrotal swelling. Transverse and

In the last 41⁄2 years 13 patients were identified with cystic ectasia of the rete testis. Ultrasound was most commonly performed for a scrotal mass or pain. Most patients referred due to concern about a testis mass had a scrotal mass separate from the testis. Median patient age in our series was 65 years. The only man younger than 55 years had von Hippel-Lindau disease. In each case numerous discrete cystic structures were closely associated in the rete testis. No solid component or calcifications were noted. There was no flow in structures in the 12 patients evaluated by color Doppler ultrasound. Most cysts were small and anechoic. However, individual cysts within the rete varied in size in each patient. In 9 cases involvement was bilateral and most bilateral cases were asymmetrical. Associated ultrasound findings included hydrocele in 10 pa-

Accepted for publication May 24, 2002. * Financial interest and/or other relationship with Alza, Bayer and Pharmacia Upjohn. 1436

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Patients with cystic ectasia of the rete testis No. pts. Median age (range) No. presentation: Scrotal mass, swelling Scrotal pain Epididymitis Abdominal mass Associated condition: Vasectomy Epididymal cyst, spermatocele Hydrocele Inguinal hernia repair Epididymal cystadenoma, von Hippel-Lindau disease Varicocele Sonographic findings: Bilat. involvement Unilat. involvement Mean cm. rete testis greatest dimension (range)

13 65

(34–81)

7 4 1 1 2 9 10 2 1 1 9 4 1.95 (1.1–2.9)

tients, epididymal cyst or spermatocele in 9, epididymal cystadenoma in 1 and varicocele in 1. Rete testis greatest dimension was 1.1 to 2.9 cm. (mean 1.95). Figure 1 shows the typical ultrasound appearance of ectatic rete testis. Figure 2 shows an ectatic rete in association with epididymal cystadenoma in a patient with von Hippel-Lindau disease. Inguinal or scrotal surgery had previously been performed in 4 patients, including 2 who underwent vasectomy, 1 patient had a history of epididymitis and 9 had spermatoceleepididymal cyst. In all except 1 patient one of these underlying conditions was potentially associated with epididymal or efferent duct obstruction. Followup varied depending on clinical circumstances. Only 1 patient underwent followup ultrasound at 6 months and no significant change was noted on this study or on physical examination. Because the condition was properly diagnosed and identified as benign, the remaining men were followed as needed with no further scheduled clinical followup. To our knowledge no patient has had a testicular neoplasm. The table lists the results. DISCUSSION

Cystic testicular lesions may be detected on as many as 10% of scrotal sonograms.3 These lesions may pose a diagnostic problem since they must be differentiated from malignant testicular tumors. While almost all malignant testicular tumors are solid lesions some, such as teratoma, may be

FIG. 1. Scrotal ultrasound shows typical appearance of cystic ectasia of rete testis.

FIG. 2. Scrotal ultrasound demonstrates ectatic rete testis in patient with von Hippel-Lindau disease and epididymal cystadenoma.

cystic or have cystic components. Hamm et al first proposed that intratesticular cysts could originate from the rete testis. They obtained histological confirmation in 8 of 13 cases (62%) but concluded that the diagnosis could be based on clinical and sonographic examination.4 Cystic ectasia of the rete testis has no significant consequences in the patient, although it may be confused with a malignant testis tumor. Benign and malignant lesions cannot always be differentiated on ultrasound but in the case of ectatic rete testis it should be possible. The seminiferous tubules merge at the apex of each lobule of the testis and connect with the tubuli recti. The tubuli recti enter the mediastinum testis, forming irregular anastomosing spaces known as the rete testis, which then lead to the efferent ducts and ultimately to the epididymis. Efferent duct or epididymal obstruction can cause sonographically detectable ectatic changes in the rete testis, offering an explanation for the association of these 2 conditions. While a testis tumor may compress the efferent ducts and, thus, cause ectasia, the solid mass should be distinct from the rete testis dilation. Cystic spaces without a solid component or adjacent solid component that are located peripherally in the mediastinum testis are pathognomonic for cystic ectasia of the rete testis. In addition, the typical patient with ectatic rete testis is older than patients with a testicular germ cell tumor.3 In our study median patient age was 65 years. In the largest reported series in the literature median age was 62 years.3 Previous reports, mostly in the radiology literature have described the radiographic and clinical characteristics of this condition.3⫺10 The largest series to date of Brown et al included 31 cases.2 Our study included 13 cases with many of the same features. As in other series, in our series patients were older than the typical age for testicular germ cell tumors. Also, a significant proportion of patients had a history of vasectomy or epididymitis, which are known to cause epididymal obstruction. Of our 13 patients 9 (69%) also had spermatoceles or epididymal cysts, which are also commonly associated with ectatic rete testis.9, 10 Spermatocele may arise from dilatation of the efferent ductules and, thus, be related to obstruction.3, 8 In our series the condition was noted bilaterally in 9 cases (69%), while in the series of Brown et al 29% were bilateral.2 In a patient in our study von Hippel-Lindau disease and epididymal cystadenoma may have also caused epididymal obstruction. In a previous study of 25 patients with von Hippel-Lindau disease 7 were noted to have epididymal cystadenoma and 1 had cystic ectasia of the rete testis.11 Cystic ectasia of the rete testis must be differentiated from other benign intratesticular lesions, notably cystic dysplasia and intratesticular varicocele. Cystic dysplasia is similar sonographically and histologically but it is a congenital lesion

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that is typical children and associated with renal or urogenital excretory duct malformations.2, 8 Cystic ectasia can be differentiated from intratesticular varicocele on color Doppler ultrasound.7 Furthermore, cystic ectasia should be distinguished from the rare adenocarcinoma of the rete testis, in which a solid mass in the rete testis should be evident.2, 9 Although ultrasonography is the preferred imaging modality for the scrotum, magnetic resonance imaging can also be performed. In 3 previous reports magnetic resonance imaging was useful for making the diagnosis of ectatic rete testis.5, 8, 10 On T2-weighted sequences they had multilobular formations and were difficult to distinguish from normal parenchyma. After contrast medium administration they did not enhance and were clearly identified as demarcated cystic malformations in the mediastinum, establishing the diagnosis.5, 8 Histologically there are 2 types of cystic ectasia, namely with and without epithelial metaplasia. Simple cystic ectasia without epithelial metaplasia is usually associated with an underlying extratesticular condition that causes excurrent duct obstruction. Cystic ectasia with epithelial metaplasia is most commonly associated with an intratesticular lesion, such as tumor or cryptorchidism.12 Simple cystic ectasia of the rete testis may also occur without an underlying condition related to obstruction. Nistal et al examined autopsy specimens from men who died of conditions unrelated to the genitourinary tract and surgical orchiectomy specimens. 12 In the autopsy series, in which simple cystic ectasia of the rete testis was noted in 1.1% of men, Nistal et al believed that ischemia was the cause of ectatic rete testis. Only 1 of the 17 men in this group had any potentially obstructive pathological condition, that is spermatocele. In contrast, all patients who underwent orchiectomy had extratesticular pathology potentially associated with obstruction, including sarcoma of the spermatic cord with epididymal invasion, tuberculous epididymitis or traumatic hematocele. Clearly patient selection for these 2 groups was different and the latter parallels the group of men with a scrotal abnormality in whom ectatic rete testis was identified on ultrasound.12 In our series limitations were the lack of histological confirmation and no further followup in most patients. Based on other reports in the literature this diagnosis can be made with confidence using the clinical and sonographic criteria outlined. Many studies cited also had limited or no followup for this reason. Typically the patient is outside of the expected age range for testicular germ cell tumors and does not have a palpable testis mass. Rather, he presents with an extratesticular abnormality, such as spermatocele, and the

pathognomonic cystic spaces without a solid component located peripherally in the mediastinum testis is identified on sonography.2 CONCLUSIONS

Cystic ectasia of the rete testis is a benign condition that has a typical appearance and may be noted incidentally on ultrasound. It may be related to urological conditions that are associated with epididymal obstruction, such as vasectomy, spermatocele or epididymitis. Knowledge of this entity and its associated conditions can aid in making the appropriate diagnosis and avoid the need for biopsy or orchiectomy. REFERENCES

1. Tchetgen, M. B. and Wolf, J. S., Jr.: Postsurgical changes in the testis: a diagnostic dilemma. Urology, 51: 333, 1998 2. Brown, D. L., Benson, C. B., Doherty, F. J., Doubilet, P. M., DiSalvo, D. N., Van Alstyne, G. A. et al: Cystic testicular mass caused by dilated rete testis: sonographic findings in 31 cases. AJR Am J Roentgenol, 158: 1257, 1992 3. Gooding, G. A., Leonhardt, W. and Stein R.: Testicular cysts: US findings. Radiology, 163: 537, 1987 4. Hamm, B., Fobbe, F. and Loy, V.: Testicular cysts: differentiation with US and clinical findings. Radiology, 168: 19, 1988 5. Meyer, D. R., Huppe, T., Lock U., Hodek, E. and Friedrich, M.: Pronounced cystic transformation of the Rete testis MRI appearance. Invest Radiol, 34: 600, 1999 6. Colangelo, S. M., Fried, K., Hyacinthe, L. M. and Fracchia, J. A.: Tubular ectasia of the rete testis: an ultrasound diagnosis. Urology, 45: 532, 1995 7. Jimenez-Lopez, M., Ramirez-Garrido, F., Lopez-Gonzalez Garrido, J. D., Mantas-Avila, J. A., Nogueras-Ocana, M., Jimenez-Verdejo, A. et al: Dilatation of the rete testis: ultrasound study. Eur Radiol, 9: 1327, 1999 8. Rouviere, O., Bouvier, R., Pangaud, C., Jeune, C., Dawahra, M. and Lyonnet, D.: Tubular ectasia of the rete testis: a potential pitfall in scrotal imaging. Eur Radiol, 9: 1862, 1999 9. Older, R. A. and Watson, L. R.: Tubular ectasia of the rete testis: a benign condition with a sonographic appearance that may be misinterpreted as malignant. J Urol, 152: 477, 1994 10. Tartar, V. M., Trambert, M. A., Balsara, Z. N. and Mattrey, R. F.: Tubular ectasia of the testicle: sonographic and MR imaging appearance. AJR Am J Roentgenol, 160: 539, 1993 11. Choyke, P. L., Filling-Katz, M. R., Shawker, T. H., Gorin, M. B., Travis, W. D., Chang, R. et al: Von Hippel-Lindau disease: radiologic screening for visceral manifestations. Radiology, 174: 815, 1990 12. Nistal, M., Mate, A. and Paniagua, R.: Cystic transformation of the rete testis. Am J Surg Pathol, 20: 1231, 1996