Leiomyosarcoma accounts for 5%–10% of soft tissue sarcoma. Paratesticular LMS originates from the spermatic cord, the scrotum or the epididymis. The spermatic cord type arises from undifferentiated mesenchymal cells of the cremasteric muscle and vas deferens. The epididymal form originates from the smooth muscle surrounding the basement membrane of the epididymis. The scrotal type arises from the dartous layer. The first two aforementioned types drain into the retroperitoneal lymph nodes in contrast with the last type, which drains into the inguinal, external and internal iliac nodes. LMS is subdivided topographically into 3 groups: LMS of the deep soft tissue, LMS of the cutaneous and subcutaneous tissue and LMS of vascular origin. According to the AJCC Cancer Staging System, paratesticular LMS should belong to the deep subtype . Its behavior is related to the site, histological grade of the lesion and the presence of nodal or distant metastases.
A recent review of 24 primary paratesticular LMS found 11 tumors in the testicular tunics, 10 in the spermatic cord, 1 in the scrotal subcutis, 1 in the dartos muscle, and 1 in the epididymis . These were from men aged 34–86 years with a peak incidence in the sixth and seventh decade [15–20]. In the study by Coleman et al. , 22% of the patients presented with metastatic disease or subsequently developed distant sarcoma. A reported survival rate is 50%–80% .
Sonography should be the initial imaging modality since it can determine the origin of the lesion and even though the imaging characteristics are not adequate to reach a single diagnosis, the heterogeneous appearance along with the irregular, often increased vascularity of the tumor may allow the diagnosis of a sarcoma. Correlation with case history of the patients and CT/MR findings can further limit the differential diagnosis and lead to a better management of the patient. The majority of the LMSs are heterogeneous lesions, although some LMSs appear to be hypoechoic. Calcifications are not mentioned in the majority of the cases described. Colour Doppler ultrasonography shows either minimal, or increased vascularity. The appearance is mostly related to the size of the lesion and the differentiation of the mesenchymal components. A non-homogeneous mass with irregular, peripheral contrast enhancement and HU between 20 and 65, indicative of cystic, solid and calcified areas were found. A thickened and edematous spermatic cord with distended vessels was also depicted. The above CT findings parallel the sonographic ones. In addition to that, absence of areas with negative HU excluded the presence of fat within the lesion .
The above-mentioned features are pathologically correlated to necrotic areas within the tumor (cystic areas), infiltration of the epididymis (epididymis not visualized), origin from the spermatic cord (high position of the lesion within the scrotum), absence of testicular infiltration (definite testicular borders), neoplastic lesions within the spermatic cord (thick and edematous appearance) and infiltration of the vessels (vessel distention within the cord)
The morphologic range of LMSs is similar to that reported in other soft tissue sites, including a tumor with prominent myxoid areas , an inflammatory LMS , and a neoplasm with epithelioid foci [24, 25]. The majority, however, display classic features of soft tissue LMS, i.e., perpendicularly oriented fascicles of cells with brightly eosinophilic cytoplasm containing delicate longitudinal fibrils and blunt-ended nuclei [26, 27]. Although some lesions have numerous pleomorphic nuclei, typical features of smooth muscle differentiation are retained; even the pleomorphic nuclei usually remain blunt-ended and paired with brightly eosinophilic cytoplasm. Pleomorphic LMSs, however, are composed predominantly of areas resembling malignant fibrous histiocytoma (showing no differentiation) but with focal zones with typical features of smooth muscle differentiation on hematoxylin and eosin staining and the appropriate immunophenotype [28, 29].
Immunohistochemistry is useful in confirming smooth muscle differentiation. Most cases stain strongly with antibodies to smooth muscle actin, muscle-specific actin, and desmin. Some also stain for CD34. Focal cytokeratin and S-100 protein positivity may occur, but myogenin stains have been negative. Spindle cell rhabdomyosarcomas in children can resemble LMSs. However, immunohistochemical stains for MyoD1 and myogenin are positive in the former and negative in the latter.
The NCI grading system identify three grades in LMS [30, 31]. Grade 1 tumors lack necrosis, had <6 mitoses/10 HPF, and have only occasional pleomorphic nuclei. Grade 2 tumors have focal necrosis (<15%) and/or mitotic activity >6 mitotic figures/10 HPF or prominent nuclear pleomorphism. The key feature of grade 3 tumors is >15% necrosis, regardless of mitotic counts or numbers of pleomorphic nuclei. Various studies indicate the prognostic importance of grading LMSs in this site because whereas most examples are low grade and behave indolently, high-grade lesions are aggressive . High-grade LMSs with pleomorphic nuclei can resemble dedifferentiated liposarcoma. This can be either identified by the presence of adjacent foci, which are sometimes very small, of well-differentiated liposarcoma, or excluded by finding more typical architectural or cytologic features of LMS with further sampling [6, 2].
Simple excision is suboptimal as repeat wide excision has demonstrated microscopic residual disease in 27% of cases and therefore warrants an additional adjuvant treatment. Radical orchiectomy and funicolectomy (inguinal approach) is the cornerstone of treatment in the management of this neoplasm, but the reported survival rates indicate the need for additional treatment .
Comprehension of the pattern of spread is essential, but this task is difficult by the rare occurrence of this disease. The most common means of dissemination are by regional lymph nodes spread (external, common iliac, hypogastric and retroperitoneal lymph nodes), haematogenous metastases (most commonly to the lungs) and by local extension (local infiltration of the scrotum, inguinal canal or pelvis, along the pathway of vas deferens). Further series suggested that lymph node dissection (especially retroperitoneal) should not be performed unless enlarged lymph nodes are encountered on CT scans or palpated during surgery.
The literature concerning benefit of adjuvant therapy after radical surgery is inconclusive because of the small numbers. Recurrence after orchidectomy alone was common in earlier reports, and adjuvant radiation has been recommended to reduce locoregional failure .
Due to the high incidence of loco-regional recurrence in the lymph nodes, 2 different treatment alternatives, prophylactic retroperitoneal lymph node dissection (RPLND) and radiotherapy, have been tried. The proponents of RPLND indicate that there is a 29% risk of metastatic potential to regional lymph nodes. A review of 101 patients by Banowsky and Schultz described 29 cases of RPLND with lymph node involvement. Of these, 17 patients had isolated lymphatic dissemination. Despite such a high incidence of lymphatic spread, no report has yet shown a significant survival benefit from the addition of RPLND to radical orchidectomy . A study from Massachusetts involved 18 patients who were subdivided into 2 groups of 9 patients. One group had surgery and the other group had surgery plus radiation therapy. Of the 9 patients treated with radical orchidectomy alone, 5 developed loco-regional failure, 2 of which were limited to lymph nodes. In contrast, there were no loco-regional recurrences among the 9 patients who received adjuvant radiation to the regional lymph nodes . These findings, which are consistent with those of Catton and colleagues, suggest that adjuvant radiation may effectively control loco-regional microscopic disease .
In conclusion, spermatic cord leiomyosarcoma, although rare, should be included in the list of differential diagnoses for a firm-to-hard lump in the cord. Apart from radical orchi-funicolectomy, there has been added benefit of adjuvant radiotherapy to prevent any loco-regional lymph node recurrence.