Rectal Staging 11 Title hidden

Case 11

High rectal cancer.


Report


Findings:


There is a 3.5 cm long circumferential neoplasm with distal margin 11 cm from the anorectal junction.


There is 1.2 cm of direct masslike invasion into the surrounding fat superiorly and proximally.


The more proximal sigmoid colon is redundant and the sigmoid meso-colon passes between the neoplasm and the bladder dome. A segment of more proximal sigmoid colon contacts the rectum in the region of the neoplasm but the neoplasm is not transmural at this site.


Anteriorly there is a thin linear band extending from the rectum to the anterior peritoneal reflection. The neoplasm is not transmural at this site.


Posteriorly, an abnormal lymph node comes to within 2 mm of the peritoneal reflection. This is at the level of S1, and in most patients the mesocolon can be mobilized at this level. No pelvic sidewall or iliac chain adenopathy.


There are two abnormal lymph nodes by morphology within the mesocolon (including the one just mentioned). No extra-mesorectal adenopathy.


No evidence of direct venous invasion.


Incidental note is made of a small utricle cyst within the prostate.


Impression:


3.5 cm T3c MRF- N1 EMVI- rectosigmoid neoplasm. A thin linear band of tissue extends from the rectum to the anterior peritoneal reflection; T4a disease extending to the peritoneal reflection cannot be excluded. More proximal loops of sigmoid colon loop back and contact the rectum in the region of the neoplasm without evidence of pathologic involvement.


Explanation


Step 1: Size and location.


The tumor is well seen on the sagittal images (1 remove annotation) and the distance to the anorectal junction is easily measured (2 remove annotation).



Step 2: Depth of invasion


The posterior wall of the rectum is curved in the location of the tumor (1 remove annotation). On an "axial" slice actually perpendicular to the posterior wall of the bowel there is direct extension of tumor into the posterior mesorectal fat over a distance of approximately 1cm (4 remove annotations). This tissue appears solid as opposed to linear and restricts diffusion (5 remove annotations). Note how streaky and indistinct the tumor extension looks on one of the axial images that is just distal to the base of the curve and therefore oblique to the posterior wall (6 remove annotations). This underscores the importance of not being oblique to the tumor.



Step 3: Mesorectal fascia


This case provides a beautiful example of where the anterior peritoneal reflection (red line in 3, remove annotations) ends and the anterior mesorectal fascia (yelllow line in 3, remove annotations) begins.


There is no tumor near the mesorectal fascia.


There is, however, a loop of more proximal sigmoid colon that loops back and contacts the rectum adjacent to the tumor (7 remove annotations). Reformatted images perpendicular to the junction of these loops of bowel show that the dark, outer muscular layer of the rectum is intact at this site (8 remove annotation, 9 remove annotation, and 10 remove annotations). Therefore this proximal loop is not involved.


There is a thin, linear tendril extending from the rectum in the region of the neoplasm to the anterior peritoneal reflection (11 remove annotation). The tumor is not transmural at this site. The peritoneal reflection is not tented or tethered. I will raise the possibility of T4a disease but my threshold is low because I know our surgeon will think that even if this is tumor he can get a clean margin here.



Step 4: Adenopathy


There were two abnormal nodes based on size > 5mm and two pathologic criteria of round and heterogeneous (12 remove annotation, and 13 remove annotation).



Step 5: Extramural vascular invasion


None.



Step 6: Incidental findings

 

Small utricle cyst in the prostate (14 remove annotation)




Discussion


Based on no mesorectal fascial involvement and the belief that clear peritoneal margins could be obtained, this patient went straight to a lower anterior resection.


There was T3c disease.

No adhesions were present between the region of the tumor and the more proximal sigmoid colon. There was no tumor in the region of the thin linear tendril approaching the anterior peritoneal reflection.


Zero of fourteen sampled nodes contained tumor.


There was extramural vascular invasion though even in retrospect I don't see signs of this on the images.