Tubular ectasia of the rete testis with spermatocele
Ultrasound examination of the scrotum revealed cystic changes in the rete testis regions of both testes, more pronounced on the symptomatic (right) side (Figures 1 through 3). In the area of the clinically palpable lump, a bilobed anechoic cystic lesion that measured 5 cm was seen. Partially replacing the right epididymis, this lump was consistent with a spermatocele. No other focal solid mass was identified in either of the testes. The left epididymis was normal. The emergency physician was informed, and the findings were discussed with the patient. The surgical team was consulted, and elective surgery was planned for the removal of the spermatocele.
Benign intrascrotal lesions are a common finding in the male population. Most such lesions occur in paratesticular tissues and are cystic in nature. Unlike testicular lesions, which are malignant in 95% of cases, paratesticular lesions are more likely to be benign.1,2
Spermatoceles are a common type of extratesticular cyst. These lesions are typically cystic dilatations of tubules of the efferent ductules inthe head of the epididymis.1 Spermatoceles have a high association with tubular ectasia of the rete testis. Examination reveals a soft, mobile, transilluminating mass that is separate from and superior to the testicle. Ultrasound shows a well-defined hypoechoic lesion that is generally 1 to 2 cm in size with posterior acoustic enhancement. These lesions may be unilocular or multilocular and usually consist of low-level echogenic proteinaceous fluid containing dead sperms.3 Calcifications have been reported, and these may mimic paratesticular neoplasms. Spermatoceles can sometimes be as large as 15 cm and may be managed by spermatocelectomy. Histologically, the lesion has a fibromuscular wall that is lined by cuboidal epithelium, although, rarely, lesions may be lined with pseudostratified epithelium and cilia.4
Tubular ectasia of the rete testis is a benign condition that results from partial or complete obliteration of the efferent ducts. It is most commonly discovered by ultrasound that is performed to evaluate a mass, swelling, or pain, as in our case. The mean age at diagnosis is 60 years, and generally patients are older than 45 years.5 Bilateral lesions have been reported in 29% to 69% of cases.6,7 Lesions are commonly associated with spermatoceles and prior scrotal surgery.6 Obstruction or sometimes ischemia appears to be the common underlying factor that results in the development of tubular ectasia.
It is important to differentiate tubular ectasia from malignant testicular tumors. On ultrasound, diagnostic keys are numerous small cystic structures within the rete testis without calcifications or solid components and a characteristic location in the posterolateral region of the testis near the mediastinum testis. No color flow is seen in these structures (Figure 1). Magnetic resonance imaging (MRI) is usually not needed because of characteristic appearances on ultrasound; however, if the MRI study is performed for other reasons, there is a confirmation of the nonenhancing cystic nature of these lesions since as they appear hypointense on T1-weighted images and hyperintense on T2-weighted images in the rete testis.
The differential diagnosis includes epididymal cystadenoma, adenocarcinoma of the rete testis, non-Hodgkin’s lymphoma, and dilatation of the seminiferous tubules secondary to testicular tumor.8-10 Epididymal cystadenoma accounts for <5% of epididymal tumors and is seen in the second and third decade in the epididymal head region. The lesion usually exhibits solid components, and there may be an association with VonHipple-Lindau syndrome.11 The other above-mentioned lesions show heterogeneity, solid components, and flow on color Doppler images. Occasionally, an intratesticular varicocele may be confused with these lesions; however, color flow and duplex Doppler ultrasound show the venous flow pattern with a characteristic venous spectral waveform that increases during a Valsalva maneuver.12
Tubular ectasia of the rete testis and spermatocele show characteristic appearances on gray-scale and Doppler ultrasound evaluation. These lesions should be recognized to prevent misdiagnosis as an ominous testicular tumor that may cause difficulty in proper counseling and management of these patients.
Prepared by David Kenny, DO, Kiran Batra, MD, Mohsen Nancy, MD, and Avneesh Chhabra, MD, Department of Radiology, Hahnemann Hospital, Drexel University College of Medicine, Philadelphia, PA.