radical prostatectomy ( rp ) is a common curative surgical treatment option in localized prostate cancer ( pca ) . pelvic lymph node ( ln ) dissection is performed in order to determine the disease stage , prognosis , and the necessary future treatment options [ 1 , 2 ] . the fatty tissue overlying the prostate is removed in order to have a better exposure of the dorsal venous complex , the puboprostatic ligaments , and the prostate apex . however , if this fatty tissue is not examined separately by a pathologist , the presence of lns and possible metastasis might be missed and underreported . this might ultimately have an impact on the postoperative disease stage , treatment , and oncologic outcomes . in our study , we investigated the histopathologic evaluation outcomes of anterior periprostatic fat ( appf ) tissues that were separately sent for pathologic evaluation in order to examine presence of lns and metastasis . overall , 129 patients who underwent rarp between january 2012 and october 2014 were included in our study . surgical procedures were performed by three robotic surgeons ( afa , aec and mdb ) . all of the rarp procedures were performed via a transperitoneal approach and patients who had history of transurethral surgery or radiotherapy were excluded from the study . during the rarp procedures , appf covering prostate , endopelvic fascia , dorsal venous complex , prostatic apex , puboprostatic ligaments , prostate - vesical junction and the bladder neck was dissected en bloc laterally and cephalad . if metastatic ln(s ) was /were detected , immunohistochemistry for prostate specific antigen ( psa ) and prostate specific acid phosphatase were performed . parameters including serum psa , prostate weight , body mass index ( bmi ) , positive surgical margins ( psm ) and gleason score ( gs ) were included for further evaluation . patients were classified according to bmi ( kg / m ) as follows : < 18.5 underweight , 18.524.9 optimal weight , 2529.9 overweight and > 30 obese . mean patient age , serum psa , prostate weight and bmi were 62.2 5.5 ( range 4574 ) , 9.3 6.3ng / dl ( range 0.330.3 ) , 60.3 27.2 grams ( range 11.0180 ) and 26.6 1.9 kg / m ( range 20.0 - 30.3 ) , respectively . overall , lns in appf tissues were detected in 14 ( 10.6% ) patients with a mean ln yield of 1.1 0.7 lns ( range , 13 ) . among those found , no additional complication or morbidity due to excision of the appf was found in any of the patients . patient characteristics postoperative pathologic stages included pt0 ( n = 1 , 0.8% ) , pt2a ( n = 22 , 17.1% ) , pt2b ( n = 15 , 11.6% ) , pt2c ( n = 62 , 48.1% ) , pt3a ( n = 21 , 16.3% ) and pt3b ( n = 8 , 6.2% ) . overall , psm were detected in 32 ( 24.8% ) patients . of the patients with pt2 disease ( n = 99 ) , psm rate was 13.1% ( n = 13 ) . of the patients with pt3 disease ( n = 29 ) , psm rate was 65.5% ( n = 19 ) . of the patients with pt2a ( n = 22 ) , pt2b ( n = 15 ) , pt2c ( n = 62 ) and pt3a ( n = 21 ) disease , lns in appf tissues were detected in 1 ( 4.6% ) , 1 ( 6.7% ) , 11 ( 17.7% ) and 1 ( 4.8% ) patient in each group , respectively . no ln was detected in appf tissue in patients with pt0 ( n = 1 ) and pt3b ( n = 8) disease . of the patients with postoperative gs 3 + 3 = 6 ( n = 63 ) , gs 3 + 4 = 7 ( n = 34 ) , gs 4 + 3 = 7 ( n = 14 ) and gs 4 + 4 = 8 ( n = 7 ) diseases , lns in appf tissues were detected in 11 ( 17.5% ) , 1 ( 2.9% ) , 1 ( 7.1% ) and 1 ( 14.3% ) patient , respectively . no ln was detected in appf tissue in patients with postoperative gs of 5 + 3 = 8 ( n = 1 ) , 3 + 5 = 8 ( n = 2 ) and 4 + 5 = 9 ( n = 6 ) . we did not have any patient with postoperative gs of 5 + 4 = 9 or 5 + 5 = 10 . of the patients , lns in appf tissues were detected in 0 ( 0% ) , 5 ( 35.7% ) , 8 ( 57.1% ) and 1 ( 7.1% ) patients of underweight , optimal weight , overweight and obese patients due to bmi , respectively . no association was detected between bmi and presence of lns or mean ln count in the appf tissue ( p > 0.05 ) . we removed appf tissue as an en bloc excision and sent it as one piece for pathologic evaluation . we generally started removing the fat laterally from one side on the endopelvic fascia from , laterally to medially , and then shift to the other side . we accumulated both sides in the middle around the superficial dorsal vein on the prostate . thereafter , we elevated it above the prostate using maryland bipolar scissors and cauterized and cut its tip over the prostatic apex by applying bipolar energy . we then pushed it back up to the junction between the prostate and bladder neck and excised the tissue by applying monopolar and bipolar cautery . following excision of the appf tissue , the area of endopelvic fascia , puboprostatic ligaments , prostatic apex , surface of the prostate and junction between prostate and bladder neck are all cleared ( figures 1 and 2 ) . prostate , endopelvic fascia , puboprostatic ligaments , junction between prostate and bladder neck are covered with fat tissue . prostate , endopelvic fascia , puboprostatic ligaments , junction between prostate and bladder neck are seen clearly following excision of the fat tissue . in our study , we identified lns in appf tissue in 10.9% of the patients . aning et al . reported 14.7% ( n = 204 ) lns in appf tissue in their series , respectively . therefore , our findings are similar to previously published studies . in our study , no metastatic ln was detected in the lymphoid tissue that was obtained from the appf tissue region overlying the prostate . however , finley et al .   found ln metastasis in 4 of 204 patients and jeong et al due to the published literature , ln metastasis rate in anterior periprostatic lymphoid tissue varied between 1.22.5% [ 58 ] . in our study , no metastatic ln was detected , which might be related to the limited number of patients in our series compared to the other published articles with a larger number of patients . in addition , studies that identified ln metastasis in anterior periprostatic lymphoid tissue had a higher volume of patients with high and intermediate risk patients , as compared to our study . in a multi - center study , kim et al . included 4261 rrp and rarp patients and there were 40 patients who had metastasis on periprostatic lns . of the 40 patients , 31 ( 77.5% ) were in a high - risk group , 6 ( 15% ) of them were in an intermediate group and 3 ( 7.5% ) of them were in a low - risk group according to d'amico risk classifications . jeong et al . detected metastatic lns in appf tissue in 3 patients that were all in the high - risk group . in our study , 55 ( 42.6% ) patients were in the high - risk group , 52 ( 40.3% ) patients were in the intermediate - risk group and 22 ( 17.1% ) patients were in the low - risk group . we summarized the outcomes of published literature on appf tissue and presence of lns in table 2 . outcomes of published literature on periprostatic fat tissue and presence of lymph nodes the european association of urology ( eau )   and national comprehensive cancer network ( nccn )   recommended extended pelvic lymph node dissection ( plnd ) in patients at 10% or greater and 7% or greater calculated risk , respectively , for ln metastases . likewise , the american urological association ( aua ) recommended plnd in patients at higher risk for nodal involvement . prognostic significance of ln metastases in prostate cancer   and assessment of rates of lns and ln metastases in periprostatic fat pads in radical prostatectomy were reported before . in our experience , we performed extended plnd in intermediate or high - risk pca patients and in those with at least 5% risk of pelvic ln involvement by pca , according to partin 's tables . in addition , we always remove appf tissue and send it separately for histopathologic evaluation in patients with low , intermediate and high - risk in order to identify the presence of lns and possible metastasis that we think could have an impact on identifying the correct stage of the disease . we remove appf tissue in low - risk patients because removal of this tissue leads to better exposure of the prostatic apex , puboprostatic ligaments , endopelvic fascia and junction of bladder and prostate . kim et al . suggested that removal of appf tissue leads to more accurate staging of the patients . in their series , due to the identification of metastatic lns in the appf tissue , 0.63% of the patients were up - staged pathologically . this finding might certainly have an impact on postoperative adjuvant treatment requirement in this patient group . the condition of regional lns is one of the most important prognostic indicators of disease free survival and overall survival in pca . if a metastatic ln is detected in appf tissue ; patients might require adjuvant hormone therapy or radiotherapy . by dissecting appf tissue anatomically , finley et al . observed that the anterior fat pad was directly connected to the obturator ln chain at the lateral pelvic wall . jeong et al . identified 3 patients with metastatic lns in appf tissue in their series of 258 patients , and 2 of these 3 also had metastasis in pelvic lns . harnisch et al . identified 4 patients who had metastasis in appf tissue in their study including 302 patients and 2 of these 4 patients had also pelvic ln metastasis . identified 4 patients with metastatic periprostatic lns but only one of them had also pelvic ln metastasis . to assess the need of adjuvant therapy , postoperative serum psa follow - up is important as well as detecting metastatic lns . in their multicenter study including 4261 patients , kim et al . reported that 6 of 40 patients with metastasis on periprostatic anterior fatty lymphoid tissue did not require adjuvant therapy at a follow - up of 1.651 months , which might suggest a therapeutic advantage . however , kim et al . separately evaluated appf tissue in three pieces as a left packet , middle packet and a right packet . in their results , , increased cost was another issue for pathological evaluation of periprostatic fat tissue . in order to decrease cost , they suggested asking for pathological evaluation of the appf tissue only in intermediate and high - risk patients . in our country , if the surgery is performed in private institutions , pathologic evaluation of the appf tissue increases costs . however , in government institutions , it does not increase overall cost because all expenses are covered by the government . in addition , because we think that complete removal of appf tissue leads to better exposure of the surgical field to the operating console surgeon , we excise it even in patients with low - risk pca . in our study , no association was detected between bmi and presence of lns or ln count in the appf tissue . bmi might have an impact on the amount of periprostatic fat rather than presence of lns . not only robotic series but also open retropubic radical prostatectomy ( rrp ) series have evaluated ln existence in appf tissue . identified lns in periprostatic region in 19 ( 5.5% ) patients of 356 in their rrp series and 4 ( 1.2% ) of them had metastasis , one of 4 patients had also pelvic ln metastasis . in this study they reported that there is no connection between periprostatic ln meta - stasis and pelvic ln metastasis , but in order to provide exact staging , pathologic examination of periprostatic lymphatic area should be a routine procedure . our study has some limitations that include limited number of patients and differences in the experiences of the surgeons that performed the cases . with increasing number of patients and having more high - risk pca patients lymph nodes might be present in the appf tissue which should be removed and sent for histopathologic evaluation following rarp . identification of metastatic lns in the appf might have an impact on postoperative staging and management of the patients . in addition , removal of appf leads to a better exposure of the surgical field .
introductionwe investigated whether anterior periprostatic fat ( appf ) tissue removed during robotic radical prostatectomy ( rarp ) contains any lymph nodes ( lns).material and methodsappf tissues removed during rarp in 129 patients were evaluated histopathologically . 
 correlation with postoperative pathologic stage was made . 
 patients with a history of previous prostate or bladder surgery and radiation therapy were excluded.resultsmean patient age , serum prostate specific antigen ( psa ) , prostate weight and body mass index ( bmi ) were 62.2 5.5 ( range 4574 ) , 9.3 6.3 ng / dl ( range 0.26 - 30.3 ) , 60.3 27.2 grams ( range 11.0180 ) and 26.6 1.9 kg / m2 ( range 20.030.3 ) , respectively . 
 overall , lns in appf tissues were detected in 14 ( 10.9% ) patients with a mean ln yield of 1.1 0.7 lns ( range , 13 ) . among those found , 
 no metastatic ln was detected . 
 of the patients with pt2a ( n = 22 ) , pt2b ( n = 15 ) , pt2c ( n = 62 ) and pt3a ( n = 21 ) disease , lns in appf tissues were detected in 1 ( 4.6% ) , 1 ( 6.7% ) , 11 ( 17.7% ) and 1 ( 4.8% ) patient in each group , respectively . among the patients , 
 lns in appf tissues were detected in 0 ( 0% ) , 5 ( 35.7% ) , 8 ( 57.1% ) and 1 ( 7.1% ) patients of underweight , optimal weight , overweight and obese patients due to body mass index , respectively.conclusionsin our series , lns were detected in around 10% of the patients . 
 therefore , this fat should , not be pushed back during rarp but should be removed and sent for pathologic evaluation . although no metastatic ln was detected in our series , the presence of metastatic lns might have an impact on the oncologic outcomes of the patients and warrants further research .