Acellular mucin in lymph nodes isolated from treatment-naïve colorectal cancer resections: a clinicopathologic analysis of 16 cases

Lymph nodes with acellular mucin harvested from treated colorectal cancers (CRC) are staged as pN0. However, there is variability among pathologists while reporting the pN stage when acellular mucin is found within nodes of untreated CRCs. While the UICC guidelines suggest staging them as pN1, the AJCC and CAP do not offer any recommendations. In order to characterize their clinicopathologic features and outcome, we compared 16 untreated CRCs (study group; mean age: 68 years) harboring nodes with acellular mucin with 34 pN0 and 25 pN1 untreated CRC controls. All tumors were unifocal; 12 (75%) were right-sided lesions. Most cases (75%) showed one node with acellular mucin (range: 1-3). MMR-deficient tumors were significantly more common in the study group (83%) compared to pN0 (33%; p = 0.006) and pN1 controls (8%; p < 0.001). The overall survival of study group patients was closer to pN0 compared to pN1 controls; however, this difference was not statistically significant. In conclusion, untreated CRC that harbor acellular mucin within lymph nodes commonly present as right-sided, MMR-deficient tumors in older women that show a non-mucinous phenotype. While the limited number of cases precludes us from making any formal recommendations about staging, we suggest that the finding of acellular mucin in a node should prompt evaluation of deeper levels (with or without cytokeratin immunohistochemistry) and submission of all pericolonic fat for additional lymph node harvest. Whether acellular mucin in nodes of untreated CRCs is related to the indolent biology of the disease, a robust local immune response or MMR deficiency requires further investigation.

Endoscopic diagnosis and treatment of complete anastomosis stenosis after colorectal resection without protective ileostomy: report of two cases and literature review

This case report describes a novel procedure for opening the lumen of a completely obstructed anastomosis when open surgery is not an option. Two patients underwent ileocecal or colorectal resection and one-stage anastomosis reconstruction without diverging ileostomy. The patients developed post-surgical abdominal distension and nausea. Emergency imaging indicated complete anastomotic obstruction and distal intestinal anastomosis emptiness. Colonoscopy revealed an anastomosis that was completely discontinued by a membranous structure. Considering that open surgery was not a viable treatment option, a minimally invasive endoscopic approach was adopted to repair the obstruction. A needle knife was used to puncture the linear white scar and contrast agent was injected under endoscopy and fluoroscopic guidance. Fluoroscopically, the proximal bowel was identified and a dual knife-mediated membrane puncture was performed. A guidewire was then passed through the incision into the proximal bowel and progressive pneumatic dilatation was performed successively with a controlled radial expansion balloon dilator until a 1.8 cm diameter dilation was achieved. After conventional balloon dilatation, the endoscope easily passed through the anastomosis without any patient discomfort. There were no postoperative signs of immediate or delayed complications. Overall, endoscopic incision and dilatation was a safe and effective treatment for acute anastomotic obstruction after colorectal surgery.