Presentation
Abnormal bowel action. Long standing.
Patient Data
Multiple small and large bowel air-fluid levels. Relatively featureless and transverse and descending colon, moderately dilated. No free gas. Findings are consistent with persistent large bowel obstruction.
No intraperitoneal free gas is identified. Small amount of intraperitoneal free fluid, mostly in the right paracolic gutter.
Marked mural thickening of a 4.5 cm segment of distal sigmoid colon, with obliteration of the lumen, and marked dilatation of large bowel proximally (up to 10 cm). There is no transit of the rectally administered contrast, confirming obstruction. Absence of dilatation of small bowel is in keeping with ileocecal valve competence.
Perirectal and perisigmoid fat stranding, with prominent lymph nodes (measuring up to 6 mm) is suspicious transmural spread of tumor, with thickening of the mesorectal fascia.
Prominent lymph nodes also demonstrated along the inferior mesenteric vascular bundle.
Mild mural thickening and a featureless appearance of the entirety of the sigmoid and descending colon are consistent with longstanding ulcerative colitis. Mucosal hyperenhancement and mesenteric hyperemia suggest superimposed active inflammation Prominent concentric mural thickening of two short segments, at the junction of the descending and sigmoid colon and in the mid descending colon, are suspicious for synchronous lesions. Small focus of mural thickening in the posterolateral descending colonic wall may represent a polyp or a residual haustral fold.
No enlarged pre or paraaortic lymph nodes.3 mm hypodense lesion within segment 7 of the liver, stable in appearance since the previous study, is too small to further characterize.
Left renal simple cortical cyst.
Patchy airspace opacity in the posterobasal segment of the right lower lobe, likely representing aspiration in this context.
Conclusion:
Obstructing sigmoid annular constricting mass, in keeping with the patient's known carcinoma, with marked large bowel dilatation.
Liquid gastrograffin was administered per rectally via a rectal tube with the balloon inflated. The procedure was uncomplicated.
Results:
Contrast filled and distended a normal appearing rectum. Tapering at the rectosigmoid junction with small amount of contrast slowly appearing 6cm proximal to this, suggesting a near complete mechanical stricture in the distal sigmoid, corresponding to the CT abnormality. Colon proximal to this not assessable.
Case Discussion
The patient went on to have a subtotal colectomy.
Histology
MACROSCOPIC DESCRIPTION:
A subtotal colectomy specimen measuring 820mm, including 15mm terminal ileum, and some proximal rectum. Located 10mm from the distal resection margin is a peritoneal reflection. There is an unremarkable appendix 30x5mm. Located 10mm from the distal resection margin, at the junction of the sigmoid colon and rectum is a fungating, stenosing mucosal tumor measuring 60mm in length. Cross sectioning show there may be invasive of the tumor into but not through the muscularis propria. There are 2 sessile polyps 70mm and 120mm proximal from the tumor. No other focal mucosal lesions are seen. The mucosa shows diffuse flattening in the distal half of the specimen, and this is associated with irregular, corrugated thickening of the wall. There is no evidence of perforation or ulceration.
MICROSCOPIC DESCRIPTION:
Sections show a moderately differentiated adenocarcinoma arising in the distal sigmoid colon. It invades through the muscularis propria into subserosa. There is focal mucinous differentiation. Lymphovascular invasion is not seen. The tumor is well clear of the radial and soft tissue margins. There is associated transmural chronic inflammation, muscular hypertrophy, neuronal hyperplasia and submucosal fibrosis. Granulomata are not seen. The macroscopically identified polypoid lesions are inflammatory polyps. Random mucosal sections from the uninvolved colon show mild crypt architectural distortion. Cryptitis and crypt abscess formation are not seen. There is no terminal ileitis. The appendix shows fibrous obliteration. No metastatic tumor is seen in 47 lymph nodes.
In immunostains, the malignant cells express MLH-1, MSH-2, MSH-6 and PMS-2 in a normal pattern.
FINAL DIAGNOSIS:
Moderately differentiated adenocarcinoma of the distal sigmoid colon on a background consistent with quiescent ulcerative colitis
AJCC Stage IB (T2b, N0, M0).
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