Seminal vesicles are a rare site for primary malignancy in GU tract1.
A variety of tumors have been reported in isolated case reports, with benign etiologies even less common than malignant. The most common cause of tumor affecting the seminal vesicles is invasion from prostate cancer (contiguous spread). Amongst all seminal vesicle malignancies, small round cell tumors (SRCT) are even rarer. Primitive Neuro-Ectodermal tumor (PNET) is the most frequently reported SRCT occurring in the seminal vesicle3. DSRCT, which is also a type of SRCT, is a very rare and aggressive tumor and to the best of our knowledge no case of seminal vesicle DSRCT has been reported in literature search.
In 1989, DSRCT was first described by Gerald and Rosai, who used the term ‘desmoplastic small cell tumour with divergent differentiation’ to describe an abdominal tumour in an 8-year-old girl resembling other small blue round cells of child- hood but showing a three lineage differention- epithelial, mesenchymal and neural4. This is a striking histological feature of this tumor. However they could not prove its true histogenesis then. Coexpression of all three components, i.e.epithelial, mesenchymal and neural, in a single cell suggests that pluripotent stem cells with divergent differentiation could be the origin of all DSRCTs. Later, the same authors and their colleagues reported 18 additional cases and concluded that this was an aggressive group of undifferentiated small round tumours5.The unique clinicopathological features of DSRC tumors are- predilection for young adults, microscopic feature of uniform cells with round nucleus and clumped chromatin, desmoplastic reaction, immunohistochemical reactivity for both epithelial and mesenchymal component, and poor prognosis7,8.
Most cases of DSRCT arise from abdominal cavity, as a multinodular growth involving serosal surfaces such as peritoneum, pleura and scrotum, and they present with abdominal mass and/or pain as the most common symptoms5. Extra abdominal DSRCT especially arising from genito-urinary system is rare6. Furman et al11 reported 27 cases of DSRCTs involving genitourinary systems out of 109 total reported DSRCTs till 1997. Out of 27, 12 were in pelvis, 5 in bladder, 3 involving ureters, 3 prostate and 3 at paratesticular region. He found pain and abdominal discomfort as the most frequent symptom followed by a mass and then voiding difficulties11. Very rarely they occur in pelvis and present with urinary frequency and lower abdominal pain6,8. Gerald et al, in their 1st reported series of intra-abdominal desmoplastic round cell tumor, observed difficulty in voiding in 13 of 19 patients5.
Definitive diagnosis of DSRCT can only be made after immunohistochemistry which shows positive reactions with antisera for epithelial, mesenchymal and neural markers with decreasing order of intensity of staining6,7. The presence of dot-like immunoreactivity with desmin also confirms diagnosis of DSRCT6. Cytogenetically, DSRCT is associated with a (11;22) (p13;q12) reciprocal translocation, resulting in fusion of EWS and WT1 genes9,10. Because of the rarity of this tumor, there are no standard treatment protocols, thus making management of DSRCT a challenging process.
Being an aggressive malignancy, DSRCT requires consideration for multimodal therapy. Multiple studies highlight the importance of combination of surgery, chemotherapy and radiotherapy which provides the greatest survival benefit12,13,14,15. There is also no preferential order of choosing the initial therapy.Debulking surgery aiming at complete resection seems to be the cornerstone of effective therapy. For instance, in a retrospective study by Lal et al17, a 3-year survival rate of 58% was reported for patients who received debulking surgery, whereas no patients in the non-surgical group survived for more than 3 years17. Tang et al retrospectively studied 18 patients, dividing them in operative vs only chemotherapy group and observed that median survival time was significantly better with operative group(more with completely resected tumor than debulking surgery), male gender and only abdominally restricted disease.
Radiotherapy did not seem to have positive effect on patient outcomes19. Zhang et al18, in the retrospective study of 48 patients, showed that surgery, effective debulking surgery, chemotherapy and any two or more combined therapies were significant prognostic factors for a longer overall survival time, confirming aggressive surgical debulking as the primary therapeutic strategy for patients with DSRCT18. Kushner et al (16) reported a 100% response rate following treatment of 12 patients with DSRCT (10 previously untreated, 2 previously treated) with a neoadjuvant chemotherapy regimen (P6 protocol) which comprised of cyclophosphamide, doxorubicin, vincristine in high doses (HD-CAV) plus ifosfamide and etoposide. This regimen was followed by aggressive surgical resection,plus post-operative whole abdominal radiation in some and a myeloablative regimen of thiotepa and carboplatin in a few patients. The median survival time was 19 months for all patients and 22 months for the 7 patients who achieved complete response.Zhang et al16 reported a case of giant pelvic DSRCT managed with surgical debulking followed by external beam radiotherapy to the whole abdomen and pelvis combined with synchronous chemotherapy (cyclophosphamide, adriamycin and cisplatin).
A significantly improved loco-regional control of DSRCT and a complete response was seen at 2 months follow up. However patient succumbed at 30 months due to recurrence and metastases.There are no universally agreed combination of drugs to be used for chemotherapy- Though regimen by Kushner et al demonstrated prolonged progression free survival, the toxicity of this regimen can be quite substantial, in form of frequent episodes of fever and myelosuppression. Aguilera et al described an alternative, less toxic outpatient home based regimen including neoadjuvant vincristine, ifosfamide, dextrazoxane/doxorubicin, and etoposide.
Neoadjuvant chemotherapy included vincristine, ifosfamide, dexrazoxane/doxorubicin, and etoposide21. Continuous hyperthermic peritoneal perfusion (CHPP) with cisplatin was given after extensive cytoreductive surgery, followed by irinotecan + temozolomide monthly, then abdominal radiation 30 Gy with simultaneous temozolomide. A total of 12 cycles of irinotecan and temozolamide were given in the outpatient or home setting. The disease free interval was of approximately 2 years, and patient maintained excellent quality of life with school attendance and playing activities.Furman et al confirmed multidrug chemotherapy to be the treatment of choice in genitourinary DSRCTs with no single combination proving survival benefit11.se