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Sigmoid adenocarcinoma with large bowel obstruction

Case contributed by Matthew Tse
Diagnosis certain

Presentation

6 days constipation, abdominal pain, distended stomach, no bowel sounds ?fecal impaction ?bowel obstruction

Patient Data

Age: 40 years
Gender: Female

Abdominal x-ray

x-ray

Grossly distended large bowel with fecal loading but paucity of rectal gas. No convincing volvulus or plain radiographic evidence of perforation. No plain radiographic evidence of colitis or toxic megacolon.
Rounded peripherally calcified structure in the midline of the lower pelvis, likely represents calcified fibroid.
Normal imaged skeleton.

Appearances would be in keeping with mechanical large bowel obstruction at the level of the distal sigmoid / rectum.

Confluent loops of dilated large bowel, transition point at distal sigmoid with irregular circumferential thickening of the distal sigmoid wall over a length of at least 4 cm. Several small pericolic nodes adjacent to the transition point. No fecal material in the large bowel distal to the transition point.
Proximal colon is grossly distended with fecal material.
Cecum measures up to 11 cm in diameter on coronal reformat.
Fecal material in the terminal ileum, which is mildly dilated; distal ileum measures up to 3.6 cm. Collapsed proximal ileum and jejunum.

Normal liver, gallbladder, adrenals, kidneys, pancreas and spleen.
Calcified uterine fibroid.

Mild bibasal atelectasis, imaged lung bases are otherwise clear.

No concerning bony abnormality.

Opinion:
Marked large bowel dilatation with transition point at distal sigmoid, at which point appearances are highly suspicious for malignant circumferential thickening. Gross upstream fecal loading of the colon.
No evidence of distal metastatic disease in the imaged volume.

Case Discussion

The patient proceeded to anterior resection with defunctioning colostomy. Small volume of free fluid identified at surgery was sampled.

Pathological analysis of the resection confirmed adenocarcinoma with disease beyond muscularis propria with positive lymph nodes and negative resection margins.

The small volume of free fluid was positive for malignant cells, though no gross macroscopic peritoneal disease demonstrated on CT and none seen surgically either.

A CT chest to complete staging was clear of malignant disease (not shown here).

Mismatch repair analysis was performed given the patient's age, no genetic anomaly found.

The patient is awaiting adjuvant chemotherapy.

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