Pathological analysis of lymph nodes in anterior prostatic fat excised at robot-assisted radical prostatectomy

Presence of lymph nodes and metastasis within prostatic anterior fat pad in radical prostatectomy patients: A single Chinese institution experience and literature review

INTRODUCTION

Limited data from China, aim to investigate the incidence and the risk fctors of lymph node metastases in the prostatic anterior fat pad (PAFP).

MATERIAL AND METHODS

Patients underwent radical prostatectomy (RP) were enrolled between March 2020 to December 2022 at a single institution. Separate pathological analysis of PAFP was performed within this area. Univariate analysis and Multivariate analysis were performed to determine the risk factor of PAFP metastasis.

RESULT

A total of 255 patients were included. The study revealed an average age of 67.72 ± 7.07 years, with a mean total tumor volume of 41.54 ± 23.79 mL, and an average Pre-op PSA of 16.85 ng/mL. Clinical T stage was divided into T2, T3, and T4 (226, 25, 4 cases, respectively), while the Clinical M stage was categorized as M0 and M1 (248 and 7 cases, respectively). Out of the patients with PAFP, 19 (7.45 %) had lymph node in PAFP, and 3 (1.18 %) patients had metastases. In the univariate and multivariate analysis, Clinical M stage and anterior primary tumor were found to be a significant high-risk factor. Among the other 15 studies, six examined the risk factors associated with it, including anterior tumors, higher tumour volume, intermediate or high risk prostate cancer.

CONCLUSION

Due to the low proportion of lymph node involvement (7.45 %) and rare tumor metastasis (1.18 %), routine separate pathological analysis of PAFP is not recommended in all RP patients unless there are anterior tumors, higher tumor volume, or intermediate/high risk prostate cancer.

Anterior prostate fat resection during prostatectomy: a histopathologic review

A common practice during robot-assisted radical prostatectomy (RARP) is to dissect the anterior prostate space and send this anterior fat sample for histological analysis to assess for the presence of any malignant tissue. Theoretically, this may help with prognostication and oncological control, however, is this a futile process? To determine the incidence of malignant tissue found in the anterior prostate (APF) samples sent for histological review. All RARP patients within a single urology centre over a 2-year period were included. The pathology results of these patients were reviewed and the proportion of patients with APF sent were analysed for presence of lymph nodes and malignant tissue. 657 patients were identified. 358 patients had APF samples reviewed by the histopathologists. 38 (10.6%) samples had lymph nodes identified within the sample. Malignant lymph node tissue was found in one patient (0.3%). Given the yield of malignancy found in APF samples is so small and the financial and time burden on pathology services, this process is not worthwhile.

The impact of histopathological analysis of anterior peri-prostatic fat in radical prostatectomy patients

Objective:

To determine the usefulness of histopathological analysis of peri-prostatic fat in a cohort of prostate cancer patients undergoing radical prostatectomy (RP) in an Australian regional centre. During RP, removal of the anterior peri-prostatic fat (APPF) is commonly undertaken; some surgeons routinely request histopathological analysis of this specimen. Previously published data show positive cancer detection in peri-prostatic fat in 0–2.5% of specimens and positive yields are mostly detected in patients with adverse pathological features.

Subjects and methods:

All patients undergoing RP in a regional urology unit in Queensland were identified. Pathology results were examined retrospectively to determine the rate of cancer involvement in APPF specimens and medical records were reviewed to assess any clinical impact.

Results:

APPF was sent for pathological analysis in 270/298 (90%) of patients undergoing RP. Prostate cancer was detected in one sample containing a single involved lymph node in a patient with Gleason 5 + 4 = 9 prostate cancer and pathological stage pT3bN1R1Mx. The presence of the cancer in the APPF did not affect the decision to offer adjuvant radiotherapy.

Conclusion:

In our population, we have identified a positive cancer yield of 0.3% in APPF specimens. When combined with all previously published series, we found positive cancer detection in 72/7391 (1%) specimens, and most patients with positive fat involvement had adverse pre-operative and final pathological features. Surgeons may consider omitting sending APPF specimens for analysis based on the low yield with little additional staging information. If surgeons continue this practice, they should consider selectively requesting analysis in intermediate- and high-risk patients.

Level of evidence:

2b

Impact of prostatic anterior fat pads with lymph node staging in prostate cancer

Background: Several reports have revealed the presence of lymph nodes in the prostatic anterior fat pad (PAFP). To date, no study has described the characteristics of Taiwanese patients harboring PAFP lymph nodes with metastatic prostate cancer involvement.

Method: Between December 2006 and May 2015, a total of 849 consecutive patients underwent robot-assisted laparoscopic radical prostatectomy with PAFP dissection. Pathological examination of the dissected PAFP was conducted to assess the presence of lymphoid tissue and prostate cancer involvement.

Results: Of the 849 patients, 76 (9.0%) had 1-3 PAFP lymph nodes. Moreover, 11 (1.3%) of the 76 patients had positive lymph node metastases of prostate cancer in the PAFP; 5 (0.6%) of the 11 patients, who had negative pelvic lymph node involvement, were upstaged because of positive metastases in PAFP lymph nodes. Among the 76 patients having PAFP lymph nodes, metastatic lymph nodes were associated with the clinical T stage, preoperative Gleason score, pathological T stage, and pathological N stage (p < 0.001). Patients with pathological seminal vesicle invasion and a higher surgical Gleason score also exhibited PAFP lymph node metastases (p < 0.005).

Conclusion: Our data show that 9.0% of patients had PAFP lymph nodes and that 1.3% had prostate cancer metastases. Additionally, 0.6% of patients were upstaged because of positive metastases in PAFP lymph nodes. Because of the pathological analysis of the PAFP, a few patients were upstaged. Thus, routine pathological analysis of the PAFP should only be conducted for those with higher preoperative prostate-specific antigen, higher Gleason score, and advanced T stage observations.

Can Anterior Prostatic Fat Harbor Prostate Cancer Metastasis? A Prospective Cohort Study

OBJECTIVES

Traditionally anterior prostatic fat (APF) hasn't been included in pelvic lymph node (LN) dissection templates following radical prostatectomy. In this study we evaluate the incidence of lymphoid tissue in the APF and the incidence of LN metastasis in APF in patients who have undergone robotic-assisted laparoscopic radical prostatectomy (RALP).

METHODS

A prospective database of RALP has been maintained between January 2010 and September 2015. APF is routinely excised and sent separately for histopathological evaluation to identify lymphoid tissue and metastatic prostate cancer.

RESULTS

A total of 629 underwent RALP. Forty-six (7.3%) of the patients had lymphoid tissue on histopathological evaluation. Two patients had meta-static disease. Both patients with positive LNs were intermediate risk on pre-operative evolution (A-PSA 16.6 ng/ml, Gleason 3 + 4; B PSA 7.3 ng/ml, Gleason 4 + 3) and upgraded on final prostate pathological evaluation to high risk disease (A-Gleason 4 + 5, pT3b, B-Gleason 4 + 3, pT4).

CONCLUSION

There appears to be lymphatic drainage to the APF from the prostate. Hence APF should be included in pelvic LN dissection templates when lymphadenectomy is contemplated in patients undergoing radical prostatectomy.

Lymph node staging in prostate cancer: perspective for the pathologist

Pelvic lymph node dissection (PLND) currently represents the gold standard method for nodal staging in the setting of localised prostate cancer and may also have a therapeutic benefit in certain patients. The histopathological evaluation of PLND specimens plays a critical role in accurate lymph node staging, however there is currently a lack of consensus regarding the optimum approach and no quality parameters are in place. In addition, there are no guidelines as to the handling of less commonly encountered nodal specimens such as those identified within the anterior fat pad. This summary provides an overview of pertinent issues regarding lymph node staging in prostate cancer, with a focus on the histopathological evaluation of resected nodal specimens. We hope that this review will further the discussion on how to achieve a more standardised approach to the processing and reporting of PLND specimens in the setting of prostate cancer.

Does anterior prostatic fat tissue removed during robotic radical prostatectomy contain any lymph nodes?

INTRODUCTION

We investigated whether anterior periprostatic fat (APPF) tissue removed during robotic radical prostatectomy (RARP) contains any lymph nodes (LNs).

MATERIAL AND METHODS

APPF 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.

RESULTS

Mean patient age, serum prostate specific antigen (PSA), prostate weight and body mass index (BMI) were 62.2 ±5.5 (range 45-74), 9.3 ±6.3 ng/dl (range 0.26-30.3), 60.3 ±27.2 grams (range 11.0-180) and 26.6 ±1.9 kg/m(2) (range 20.0-30.3), 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, 1-3). 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.

CONCLUSIONS

In 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.

Oncologic outcomes in men with metastasis to the prostatic anterior fat pad lymph nodes: a multi-institution international study

Background

The presence of lymph nodes (LN) within the prostatic anterior fat pad (PAFP) has been reported in several recent reports. These PAFP LNs rarely harbor metastatic disease, and the characteristics of patients with PAFP LN metastasis are not well-described in the literature. Our previous study suggested that metastatic disease to the PAFP LN was associated with less severe oncologic outcomes than those that involve the pelvic lymph node (PLN). Therefore, the objective of this study is to assess the oncologic outcome of prostate cancer (PCa) patients with PAFP LN metastasis in a larger patient population.

Methods

Data were analyzed on 8800 patients from eleven international centers in three countries. Eighty-eight patients were found to have metastatic disease to the PAFP LNs (PAFP+) and 206 men had isolated metastasis to the pelvic LNs (PLN+). Clinicopathologic features were compared using ANOVA and Chi square tests. The Kaplan-Meier method was used to calculate the time to biochemical recurrence (BCR).

Results

Of the eighty-eight patients with PAFP LN metastasis, sixty-three (71.6 %) were up-staged based on the pathologic analysis of PAFP and eight (9.1 %) had a low-risk disease. Patients with LNs present in the PAFP had a higher incidence of biopsy Gleason score (GS) 8–10, pathologic N1 disease, and positive surgical margin in prostatectomy specimens than those with no LNs detected in the PAFP. Men who were PAFP+ with or without PLN involvement had more aggressive pathologic features than those with PLN disease only. However, there was no significant difference in BCR-free survival regardless of adjuvant therapy. In 300 patients who underwent PAFP LN mapping, 65 LNs were detected. It was also found that 44 out of 65 (67.7 %) nodes were located in the middle portion of the PAFP.

Conclusions

There was no significant difference in the rate of BCR between the PAFP LN+ and PLN+ groups. The PAFP likely represents a landing zone that is different from the PLNs for PCa metastasis. Therefore, the removal and pathologic analysis of PAFP should be adopted as a standard procedure in all patients undergoing radical prostatectomy.

Electronic supplementary material

The online version of this article (doi:10.1186/s12894-015-0070-1) contains supplementary material, which is available to authorized users.