Anatomical lymph node mapping in normal mesorectal adipose tissue

Widespread anorectal lymphovascular networks and tissue drainage: analyses from submucosal India ink injection and indocyanine green fluorescence imaging

AIM

Abdominoperineal resection is associated with poor prognosis in patients with advanced lower rectal cancer. This study aimed to analyse the functional lymphovascular network and tissue drainage in the anorectal region.

METHODS

In this descriptive study, we performed microanatomical evaluations and intra-operative imaging analysis in a cadaver and patients with rectal cancer. Specimens with India ink injection were collected from a cadaver and from six patients who underwent abdominoperineal resection. Intra-operative indocyanine green fluorescence imaging was performed on four patients who underwent surgery for lower rectal cancer. India ink was injected into the submucosa at the dentate line of specimens. Tissue sections were examined by immunohistochemistry for D2-40 and CD31. Intra-operative indocyanine green was injected into the submucosa at the dentate line. Lymph flow was traced using a near-infrared camera system.

RESULTS

Fascia branching from the rectal longitudinal muscle layer extended to the posterior hiatal ligament and lateral endopelvic fascia connective tissue lamina on the surface of the levator ani muscle. The fascia contained veins labelled with ink in their lumina and initial lymphatics. Intra-operative indocyanine green fluorescence imaging revealed extensive lymph flow from the muscle layer of the anal canal to the hiatal ligament and endopelvic fascia along the longitudinal muscle layer fibres.

CONCLUSIONS

The anorectal region contained widespread venous and lymphatic networks in proportion to its specific connective tissue framework around the longitudinal-muscle-layer-extending muscle bundles, which provides extensive networks for tissue fluid and cells.

Effect of high ligation on survival of patients undergoing surgery for primary colorectal cancer and synchronous liver metastases

Background

Although R0 surgery is recommended for stage IV colorectal cancer, the degree of required lymphadenectomy has not been established. The aim of this study was to investigate the prognostic impact of high ligation (HL) of the feeding artery and the number of retrieved lymph nodes after R0 surgery for colorectal cancer and synchronous colorectal cancer liver metastasis (CRLM).

Methods

This was a multi‐institutional retrospective analysis of patients with colorectal cancer and synchronous CRLM who had R0 surgery between January 1997 and December 2007. Clinical and pathological features were compared in patients who underwent HL and those who had a low ligation (LL). Kaplan–Meier analysis was performed to estimate the effect of HL on overall survival (OS). The impact of several risk factors on survival was analysed using the Cox proportional hazards model.

Results

Of 549 patients, 409 (74·5 per cent) had HL. Median follow‐up was 51·4 months. HL significantly improved the 5‐year OS rate (58·2 per cent versus 49·3 per cent for LL; P = 0·017). Multivariable analysis revealed HL to be a significant prognostic factor compared with LL (5‐year mortality: hazard ratio (HR) 0·68, 95 per cent c.i. 0·51 to 0·90; P = 0·007). In subgroup analysis, the positive effect of HL on OS was greatest in patients with lymph node metastasis.

Conclusion

HL of the feeding artery was associated with improved OS in patients with colorectal cancer and synchronous CRLM after R0 surgery.

Size and distribution of lymph nodes in rectal cancer resection specimens

BACKGROUND

The detection of lymph node involvement is fundamental to the staging of rectal cancer, and aids in prognostication and identification of patients who will benefit from adjuvant therapy. The anatomical variation in distribution and size of mesorectal lymph nodes has received scant attention.

OBJECTIVE

This study aimed to determine the size and distribution of lymph nodes in rectal cancer resection specimens.

DESIGN

This was a prospective, observational study of rectal cancer resection specimens analyzed by a single histopathologist.

SETTING

This study was conducted from January 2007 to July 2013 at the authors' institution.

PATIENTS

Two hundred forty-four consecutive patients underwent resection for rectal cancer.

MAIN OUTCOME MEASURES

The size and distribution of lymph nodes in the resection specimens and the anatomical position of mesorectal lymph nodes in relation to the peritoneal reflection, tumor, and anal verge were recorded.

RESULTS

A total of 10,473 lymph nodes were retrieved in 244 patients (75 women; median age, 68 years (interquartile range, 59-75 years)). One hundred seventy-three anterior resection and 71 abdominoperineal resection specimens were analyzed. Median lymph node yield was 41 lymph nodes (interquartile range, 31-52); 344 of 10,473 (3.2%) lymph nodes were positive. Lymph nodes were distributed in the mesorectum, sigmoid mesentery, and vascular pedicle in 40%, 32%, and 28% of the patients. Sixty-eight percent of mesorectal lymph nodes were above the peritoneal reflection. Mesorectal lymph node distribution in relation to the tumor was 53% above, 36% adjacent to, and only 11% below the tumor. Ninety-five of 334 (28%) positive nodes were ≤3 mm in diameter.

LIMITATIONS

Resection specimens analyzed by other pathologists (<5%) have not been included, and fat clearance techniques were not used to retrieve lymph nodes.

CONCLUSIONS

To ensure accurate nodal staging of rectal cancer, both resection and subsequent pathological evaluation should focus on the mesorectum in close proximity to the tumor and along the superior rectal artery. Small lymph nodes (<3 mm in size) should not be overlooked, and lymph node metastasis to the sigmoid mesentery is rare (see Video, Supplemental Digital Content 1, http://links.lww.com/DCR/A177).

Clinico-pathological factors influencing lymph node yield in colorectal cancer and impact on survival: analysis of New Zealand Cancer Registry data

BACKGROUND

Lymph node yield (LNY) and lymph node ratio (LNR) are recognized as independent prognostic factors in colorectal cancer (CRC).

OBJECTIVES

To examine the relationship between LNY and other clinico-pathological variables, and the prognostic value of LNY and LNR on patient survival in CRC.

METHODS

The clinico-pathological and survival data for patients diagnosed from January 2000 to July 2012 were retrieved from the New Zealand Cancer Registry. Multiple linear regression was used to identify clinico-pathological factors influencing LNY, and Cox regression was used to determine the association between LNY and LNR and patient survival.

RESULTS

14,646 patients were included in the study (mean age 70.3 years, 50.1% male). Mean LNY was 17.4. Younger age, right-sided disease, higher T stage, female sex and no neoadjuvant radiotherapy (rectal cancer) were all associated with higher LNY (P ≤ 0.001). Overall survival in Stage I-III disease increased with higher LNY (for LNY ≥ 12, HR = 0.67, 95% CI 0.64-0.72; P < 0.001). Survival in Stage III-IV disease was inversely related to LNR (HR = 0.56, 95% CI 0.51-0.62; P < 0.001).

CONCLUSION

LNY is influenced by patient age, site of disease and T stage. LNY (Stage I-II) and LNR (Stage III-IV) have independent prognostic value in CRC.

Multiple metastases of soft tissue visualized by technetium-99m-methylene diphosphonate scintigraphy: a case report

Introduction

Lungs and liver are the most common sites of colorectal cancer metastases after regional lymph nodes, but metastases to unusual sites are reported. Heterotopic bone formation in soft tissues from colorectal cancer is a rare metastatic occurrence.

Case presentation

We present the case of a 29-year-old Caucasian man affected by colon adenocarcinoma with multiple soft tissue metastases visualized by magnetic resonance imaging, computed tomography scan and scintigraphic bone scan. We suppose that these findings can be due to the fact that the tracer is concentrated in the ossification nidus of soft metastases.

Conclusions

Our experience suggests that, in the presence of colon adenocarcinoma, a bone scan could be a sensible tool to highlight bone lesions or heterotopic bone nidus in soft tissues and that any subcutaneous lesion should be resected to avoid underestimating a potential malignancy.

The complexity of the count: considerations regarding lymph node evaluation in colorectal carcinoma

In patients with colorectal carcinoma, studies have reported improved survival with increasing numbers of retrieved lymph nodes. These findings are puzzling, as increased node sampling was not correlated with significant change in disease staging. Although the physiologic processes underlying this correlation between number of lymph nodes sampled and survival remain unknown, the reported correlation has caused modifications to clinical and non-clinical practices. Herein, we review the literature and discuss potential etiologies responsible for the observed increased survival statistics. Literature regarding colorectal lymph node anatomy, molecular aspects of colorectal cancer, changes in tumor characteristics and utilization of lymph node sample numbers are evaluated. In addition, we present the mathematical concepts available for probabilistic prediction of diagnostic confidence based upon sample size. From evaluation of the aggregate literature, certain facts emerge which are not easily identified within the individual studies. Colorectal carcinoma appears to encompass a number of individual disease entities with different physiologic characteristics and likelihoods of metastasis. In addition, it appears the improved survival is likely multifactorial including effects from intrinsic tumor biology and tumor-host interactions along with ever changing clinical practices. Finally, because lymph node count is dependent on a number of variables and is correlated, but unlikely to be causally associated with survival, use of this number as a quality indicator is unwarranted. Based on statistical considerations, the current recommended goal of 12-15 recovered lymph nodes without evidence of metastatic disease provides approximately 80% negative predictive value for colorectal carcinoma metastasis.

Clinicopathologic factors associated with lymph node retrieval in resectable colon cancer: a Veterans' Affairs Central Cancer Registry (VACCR) database analysis

BACKGROUND

A long-term determinant of survival in resectable colon cancer is the involvement of regional lymph nodes. We evaluated the clinicopathologic factors associated with lymph node retrieval.

METHODS

We conducted a retrospective analysis of patients with resected stage I-III colon cancer in the Veteran's Affairs Central Cancer Registry between 1995 and 2008. One-way ANOVA compared the differences between various groups. Multivariate logistic regression analysis was performed to determine the factors associated with the harvest of 12 or more lymph nodes for pathologic examination.

RESULTS

There were 19,240 patients with resectable colon cancer included in our analysis. Mean number of lymph nodes retrieved increased with later year of diagnosis, higher overall stage, higher T descriptor, age <65 years, poorer differentiation and right-sided tumors (P < 0.01 for all covariates). These aforementioned factors are also associated with an increased probability of retrieving 12 or more lymph nodes after surgical resection (P < 0.01 for all covariates).

CONCLUSIONS

Later year of diagnosis, younger patients, right-sided tumors, poorer differentiation, higher T descriptor and overall stage are associated with increased number of lymph nodes retrieved. These may indicate the presence of an immunological response of tumor versus host affecting lymph node retrieval.