Variations in Laminar Arrangements of the Mesocolon and Retropancreatic Fascia: a Histological Study Using Human Fetuses Near Term

OBJECTIVE

The embryonic mesentery of the ascending and descending colons as well as the pancreas disappears due to peritoneal fusion, but there might be no or few photographic demonstrations of the intermediate morphologies during the process. The aims of this study were to characterize the morphological relationship of the interface between the renal fascia and peritoneum.

METHODS

Fourteen late-stage fetuses with crown rump lengths (CRLs) of 250-325 mm (gestational age: 30-38 weeks) were histologically examined.

RESULTS

The renal fascia, a thick or thin layer consisting of densely-distributed abundant fibers, was consistently separated from the renal capsule by a perirenal space containing fat. The transverse colon carried a typical mesocolon histologically different from the renal fascia. The ascending and descending mesocolons were irregularly divided into multiple laminae and the colic external longitudinal muscle appeared to directly contact the renal fascia. There was a spectrum of variations from multiple laminae to a single thick fascia between the pancreatic body and the left kidney or adrenal.

CONCLUSIONS

A fascial development after retroperitoneal fusion of the mesentery showed great individual and site-dependent differences in proportion of 1) a complete fusion with the renal fascia and 2) a multilaminar structure including the remnant peritoneum. These variations masked the likely stage-dependent change.

Complete mesocolic excision an assessment of feasibility and outcome

Surgery is the most important factor for radical treatment of colon cancer, and the long-term prognosis can be improved by improving the surgical treatment without increased risk of perioperative mortality. Complete mesocolic excision (CME), in which more extensive lymph node (LN) dissection is performed, has been shown in single-centre studies with historical controls to be associated with better oncological outcome. However, better evidence is needed. The main purpose of this PhD thesis was to investigate whether CME could be implemented in a colorectal surgical department in Denmark, whether more extensive dissection could demonstrate LN metastases outside the mesocolon, and to demonstrate a possible association between CME and improved oncological results without increased risk of perioperative mortality. This thesis includes five articles. Two articles (IV and V) are based on the population of patients undergoing elective resection for colon cancer in the Capital Region from June 2008 to December 2013. Two articles (II and III) are based on data from the local colon database in Hillerød, and the last article (I) is a systematic review concerning the risk of metastases from colon cancer to the central LNs in the mesocolon. Article I found a risk of metastases in central LNs to be reported in 1-22% of the cases of right-sided colon cancers, and in up to 12% of the cases with sigmoid tumours. The populations included and methods used in the studies were very heterogeneous and no definitive conclusions can be drawn. It was shown in article II that the surgical quality, i.e. quality of the specimens assessed by the pathologists, improved with implementation of CME in Hillerød. The vascular tie was higher, and the implementation was not associated with an increased risk of perioperative mortality. Article III demonstrated a risk of LN metastases in the gastrocolic ligament along the stomach for tumours located in the transverse colon, in the ascending or descending colon close to or in the flexures. It occurred in 4% of all patients and 13% of the patients with LN metastases in mesocolon. Resection of these LNs seems advisable for these tumour locations. Article IV showed no association between increased perioperative mortality and CME (n = 529) when compared with non-CME (n = 1,701). The 30-day mortality was 4.2% after CME compared with 3.7% after non-CME (p = 0.605), and the 90-day mortalities were 6.2% and 4.9% (p = 0.219) respectively. Odds ratios for 30-day and 90-day mortalities after CME were respectively 1.07 (95% confidence interval: 0.62-1.80) and 1.25 (0.77-1.94) in the multi-variable logistic regression analyses. Postoperative respiratory failure and need for vasopressors were significantly more frequent in the CME group and, besides CME itself, could be associated with the fewer laparoscopic resections and more severe preoperative comorbidity in the CME Group. Article V demonstrated an association between higher four-year disease-free survival for stage I-III tumours and CME (n = 364) when compared with non-CME (n = 1,031). Most notable was the difference for stage I and II cancers. The four-year disease-free survival for stage I was 100% in the CME group compared with 89.8% (83.1-96.6) in the non-CME group (p = 0.046). For stage II the disease-free survivals were 91.9% (87.2-96.6%) in the CME group and 77.9% (71.6-84.1%) in the non-CME group (p = 0.0033), and for stage III 73.5% (63.6-83.5) and 67.5% (61.8-73.2) (p = 0.13) respectively. In the multivariable Cox regression models, CME was a significant predictive factor for higher dis-ease-free four-year survival for stage I-III patients with hazard ratios (HR) for CME of 0.59 (0.42-0.83, p = 0.0025). For stage II the HR was 0.44 (0.23-0.86, p = 0.018) and for stage III 0.64 (0.42-1.00, p = 0.048).

Volvulus of the small intestine caused by right paraduodenal hernia: a case report

This report describes a very rare case of right paraduodenal hernia presenting as volvulus of nonherniated small intestine. A 12-year-old boy presented with sudden onset of lower abdominal pain, and emergency laparotomy was performed on a diagnosis of small intestinal obstruction. Laparotomy confirmed right paraduodenal hernia and volvulus of the small intestine out of the hernia sac.