Obstructing sigmoid adenocarcinoma

Case contributed by Michael P Hartung
Diagnosis certain


Abdominal distension and pain.

Patient Data

Age: 75 years
Gender: Male

Diffuse colonic dilation which tapers at an area of mass-like, circumferential thickening in the sigmoid colon. Small amount of free fluid. Pseudopneumatosis of the cecum (intraluminal, dependent gas surrounding stool only, which stops at the air-stool/fluid transition). 

No adenopathy. No metastases. 




Received unfixed labeled sigmoid is a 32 cm length of colon with a diameteer of 5 cm and attached pericolonic adipose tissue with a stich marking the proximal end. Opening reveals a circumferential 4 x 3 cm ulcerated tumor which is 4 cm from the distal margin. In addition, 2.0 cm from the tumor is a 3 x 1.5 cm polypoid mass which is 1 cm from the distal margin. Representative sections are submitted as follows:


Specimen: Rectosigmoid / Histologic Type: Both adenocarcinoma / Histologic Grade: Both low grade (moderately differentiated) / Microscopic Tumor Extension: Larger tumor into pericolonic fat; smaller tumor into muscularis propria.

Margins: Free of tumor / Lympho-Vascular Invasion: None seen / Perineural Invasion: None seen / Tumor Deposits: Not present / Lymph nodes: Nineteen benign nodes.


Colon, rectosigmoid, resection - Adenocarcinoma, pT3 N0.


Case Discussion

Both benign and malignant causes of colonic obstruction can occur. Benign strictures can be from ischemia or inflammation (e.g. recurrent diverticulitis). 

In this case, the mass-like thickening and enhancement at the site of transition should strongly raise the suspicion for a malignant stricture due to scirrhous adenocarcinoma, even in the absence of adenopathy or tumor elsewhere. 

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