A tomografia de retroperitôneo normal em adolescentes com rabdomiossarcoma paratesticular afasta necessidade de linfadenectomia ? Does negative retroperitoneal CT in adolescents with paratesticular rhabdomyosarcoma preclude the need of retroperitoneal lymph node dissection ?

We report on a 16-year-old male with paratesticular rhabdomyosarcoma who underwent retroperitoneal lymph node dissection due to a stage I tumor (normal retroperitoneal computed tomoghaphy). The surgical finding was three enlarged nodes, positive for metastatic disease. Patient was referred to adjuvant chemotherapy. This case suggests that the Intergroup Rhabdomyosarcoma Study Group IV protocol is subject to questions regarding adolescents with paratesticular rhabdomyosarcoma, and that negative retroperitoneal CT does not preclude the need of lymph node dissection.


INTRODUCTION
Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in childhood, with peaks of incidence between the ages of 2 to 4 years and 15 to 19 years.It accounts for about 6.5% of all pediatric malignancies with an annual incidence of 4 to 7 cases per million (1) .Paratesticular rhabdomyosarcoma (PT-RMS) arises from the mesenchymal tissues of the spermatic cord, epididymis, testis and testicular tunics, and represents 7% of all RMS (2) .The current multimodal treatment has allowed significant improvement in disease control, with a survival rate up to 80% in 2 years (3) .
The suggested use of local treatments, such as retroperitoneal lymph node dissection (RPLND) is controversial because PT-RMS is considered a systemic disease (2) .Data from the Intergroup Rhabdomyosarcoma Study Group (IRS-I to IRS-III) suggest that negative retroperitoneal computed tomography (CT) could downstage pathological stage II patients as clinical stage I and interfere in patient's survival rate.
We report on a 16-year-old patient with PT-RMS, who presented negative retroperitoneal CT-scan and the RPLND performed 15 days later confirmed positive nodes not detected in the 7-mm CT slices.

CASE REPORT
A 16-year-old male presented with a 7-month history of slow growing mass in the right scrotum.The ultrasonography (US) suggested a paratesticular tumor (Figure 1).Laboratory tests showed ß-HCG < 1.2 IU/L (< 5) and alpha-fetoprotein of 0.92 ng/mL (0.5 to 5.5).A radical inguinal orchiectomy was performed and pathological examination revealed a 6-cm paratesticular embryonal RMS.Chest x-ray was normal; the retroperitoneal 7-mm slice CT reviewed by a senior radiologist at our institution was negative for lymph nodes (Figure 2).We decided to perform a modified RPLND because of the post-pubertal presentation.During dissection three enlarged nodes were identified (Figures 3 and 4) and confirmed to be metastatic by pathological evaluation.Patient was referred to adjuvant chemotherapy.

DISCUSSION
The Intergroup Rhabdomyosarcoma Study Group (IRSG) established the guidelines for management of rhabdomyosarcoma (RMS) (3) .Multimodal treatment has considerably improved the outcome of patients with PT-RMS.The superficial location enables detecting early signs and symptoms.Furthermore, the paratesticular site often allows curative surgery with complete excision of the tumor.The high proportion of non-metastatic embryonal tumors that represent the favorable histological subtype may be responsible for high treatment responsiveness.
The introduction of CT to identify lymph node involvement in IRS-IV led the authors of the International Rhabdomyosarcoma Study Group to assume that RPLN was not necessary if CT was negative.However, Hermans et al. found that retroperitoneal lymph node (RPLN) status in adults with PT-RMS staged with CT scanning was incorrect for 58% of their patients (4) .Yet, there are controversies in the management of PT-RMS, specifically if CT scanning can exclude retroperitoneal involvement.Wiener et al. (5) compared patients treated on IRSG III (n = 100) or IRSG IV (n = 134) and found that there was a significant change in the distribution of patients with group I versus II tumors from IRSG-III to IRSG-IV (group I, 68% in IRSG-III versus 82% in IRSG-IV).This was the result of decreased node recognition when CT was used to stage in IRSG-IV and was most notable for adolescents (> 10 years).
Some authors confirmed that the majority of patients classified as groups I and II are prepubertal, while most patients in groups III and IV are postpubertal (6) .Consequently, the 5-year event-free survival rates in the prepubertal and postpubertal series are also different and in a series with 44 patients, reviewed by Ferrari et al., the survival rate was 91 and 60%, respectively (6) .These data suggest the important prognostic role of age and imply biological differences between PT-RMS of childhood and of adolescence, which may be used as an argument for more aggressive approach when treating adolescents.In the same study, abdominal CT correctly staged only 8 of 19 cases (42%).If the therapeutic regimen and subsequent outcome are determined based on sites and volume of disease, then staging is important.This fact is true for PT-RMS, as Wiener et al. demonstrated that node involvement is associated with decreased patient survival, and increased risk of relapse and death (7) .
Therefore, if clinical staging is poor and the therapeutic regimen is altered based on pathological staging, RPLND would appear to confer a benefit based on improved staging alone.In our case, a negative CT-scan reviewed by an experienced radiologist would have taken us to propose a wrong chemotherapy regimen if surgery was not performed.Nevertheless, arguments against RPLND for PT-RMS do exist.For clinical group I patients some argue that chemotherapy is able to eradicate micrometastases and omitting RPLND will reduce short and longterm morbidity without affecting survival.We believe that morbidity of modern nerve sparing RPLND is minimal and acceptable and most importantly, stage II patients should receive additional therapy (RPLND, radiation or more intensive chemotherapy) beyond the standard administration of cyclophosphamide, doxorubicin and vincristine.Another argument in favor of RPLND was made by Raney et al. in a review of paratesticular cases from the Intergroup Rhabdomyosarcoma Studies groups I and II (8) .