[916] How Should Hilar Paratesticular Soft Tissue Invasion Be Staged in Germ Cell Tumors (GCT)

A Yilmaz, T Cheng, F Elliott, K Trpkov. Calgary Laboratory Services and University of Calgary, Calgary, AB, Canada; Tom Baker Cancer Center, Calgary, AB, Canada; Calgary, AB, Canada

Background: Extratesticular extension (ETE) is defined as tumor penetration through the entire thickness of tunica albuginea. To our knowledge, only one study evaluated the ETE in GCT and found that it occurs only in the testicular hilum. Although invasion of extratesticular structures, such as tunica vaginalis, epididymis, spermatic cord and scrotum is recognized in the current TNM system, involvement of hilar paratesticular soft tissue (PST) is not addressed.
Design: We investigated the frequency and the location of ETE in GCT, and focused on the hilum of the testis. We reviewed the slides and the pathology reports of 289 consecutive testicular GCT (209 seminomas, 80 mixed GCT), which were resected in our institution between 09/1999 and 12/2006. When ETE was identified, we assessed the tumor extension into the following structures: tunica vaginalis, epididymis, hilar (PST) and spermatic cord.
Results: ETE was identified in 58 (20%) of all testicular GCT: 34 (16%) in seminomas and 24 (30%) in mixed GCT. When ETE was present, it involved the hilar (PST) in all cases and in 36 (62%), it was the only extratesticular site involved without invasion of other structures. Additional invasion of epididymis and spermatic cord was found in 16 (27%) and 10 (17%) tumors with ETE, respectively. Tunica vaginalis invasion was found only in 2 (3%) of tumors with ETE, which represented 0.7% of all GCT. Four tumors demonstrated extensive hilar involvement and it was difficult to distinguish hilar (PST) invasion from a true spermatic cord invasion. When we compared histopathological variables between tumors with and without ETE, presence of ETE was strongly associated with vascular invasion (p<0.001) and rete testis invasion (p<0.001). Tumors with ETE had larger mean size vs. tumors without ETE (4.9 vs. 3.8cm; p=0.027). Distribution of histologic tumor type (seminoma vs. mixed GCT) did not differ significantly in tumors with and without ETE.
Conclusions: ETE occurs exclusively through the hilum of the testis. Most common location of ETE is the hilar (PST). ETE is strongly associated with presence of vascular and rete testis invasion and it is more commonly seen in larger tumors. Tunica vaginalis invasion is an exceptionally rare finding in GCT. Hilar (PST) invasion should be incorporated in the future revisions of the TNM staging for testicular GCT and further studies should validate its prognostic significance.
Category: Genitourinary (including renal tumors)

Monday, March 9, 2009 1:00 PM

Poster Session II # 97, Monday Afternoon