Introduction

Paratesticular neoplastic lesions are rare. Within these, paratesticular sarcomas are even less frequent, but represent the most common type of genitourinary sarcoma. They arise within the scrotum and originate in the soft tissue that surrounds the testicle including the epididymis, spermatic cord, dartos, and tunica vaginalis. Given the low frequency of the disease, there are limited data to guide management, presenting a diagnostic and therapeutic challenge for clinicians.^1,2 The cornerstone of treatment is surgical resection, combined with histology-specific chemotherapy and radiotherapy. We present the case of a right epididymal synovial sarcoma in a 60-year-old male.

Case Report

The patient was on regular urological follow-up for a progressive increase in size of his right testicle and was referred to our institution with a scrotal ultrasound that showed a 28-mm solid right “extratesticular” lesion of neoplastic appearance, of possible epididymal origin, and in close contact with the right testicle, causing deformation of its upper pole. An MRI of the abdomen and pelvis was performed showing a right paratesticular tumor that seemed to arise from the tunica vaginalis; positron emission tomography–CT did not show any distant dissemination. The patient underwent an extended right radical orchiectomy with high ligation of the spermatic cord without incident, and his postoperative recovery was uneventful. The histopathology report confirmed a 4.2-cm tumor replacing the epididymis, corresponding to a high-grade spindle cell sarcoma with areas of necrosis and marked nuclear pleomorphism (Figure 1). In addition, satellite nodules in the tunica vaginalis and secondary hydrocele were identified. No lymphovascular invasion or spermatic cord involvement was observed. Smooth muscle actin, epithelial membrane antigen, and CD99 (cluster of differentiation 99) antigen were positive on immunohistochemistry (Figure 2, A-C). These histological and immunohistochemical findings were consistent with a grade 3 monophasic synovial sarcoma. The patient also received intensity-modulated radiation therapy: 3,000 cGy in 5 sessions in the scrotum, and after 1 session of 800 cGy in the abdomen. He was monitored with positron emission tomography–CT, which revealed multiple retroperitoneal and pulmonary lesions, possibly secondary. It was discussed in the oncology committee and a decision was made to proceed with complementary chemotherapy. OncoDEEP (a comprehensive biomarker test) demonstrated that the patient is a candidate for cyclins. He is currently awaiting follow-up.

Discussion

Paratesticular tumors are infrequent scrotal masses, accounting for less than 5% of all scrotal tumors,³ with a slow and indolent onset, and in most cases are of a benign nature (70%).⁴ The most common subtypes of paratesticular sarcomas are liposarcomas, leiomyosarcomas, and rhabdomyosarcomas, and they occur most frequently between the second and sixth decade of life.^2,5 Ultrasound is the most widely used diagnostic method; however, it does not always accurately achieve a differential diagnosis prior to surgery. In the case where the diagnosis is equivocal, MRI can further characterize the lesion, defining the location of the tumor and its relationship with the surrounding structures.^1,2,6 CT of the abdomen and pelvis, and the thorax, is typically the modality of choice for staging tumor spread.^2,4

Soft-tissue sarcomas account for 1% of all adult malignancies.⁷ Synovial sarcoma is a mesenchymal neoplasm that appears in children and young adults, and most frequently affects the extremities, representing 5%-10% of all histological types of soft-tissue sarcomas. It is usually regarded as a high-grade tumor and patients develop metastases particularly in the lungs. Unusual locations have been reported, including the mediastinum, lungs, peritoneum, and the testis.⁸ Paratesticular synovial sarcoma is an extremely rare malignant tumor. Standard management consists of wide excision of the tumor, with clear margins in order to reduce the risk of local recurrence.^2,9,10 Age of presentation, tumor size, histological tumor grade, proximity to the inguinal canal, and surgical margins are important prognostic factors that have been implicated in recurrence.^2,9,11 Furthermore, achieving clear margins in the first instance is key to disease-free survival. Adjuvant therapy has been described for larger and deeper synovial sarcomas.^9,10 Chemotherapy does not have an established role, and its routine use is yet to be supported.^2,12 On the other hand, radiotherapy has promising data in reducing locoregional recurrence; however, there are few published studies that support it.^2,12,13 Long-term follow-up is recommended for all patients, as recurrences have been seen several years after treatment. The majority of high-grade tumors tend to recur, namely in retroperitoneal nodes or systemically, and thus, should be followed closely.^2,4

Conclusions

Synovial sarcoma should be considered in the differential diagnoses of paratesticular soft-tissue tumors because of the importance of early and aggressive management. According to the literature, most paratesticular sarcomas progress without recurrence, making our case exceptional considering the histological subtype and the rapid imaging progression it presented.