Diagnostic Ultrasound - Abdomen and Pelvis

Large Bowel Malignancy
Diagnoses: Bowel
TERMINOLOGY
• Malignant lesion of colon or rectum
IMAGING
• Best diagnostic clue: Focal segmental thickening or mass
lesion of colon or rectum
• US image interpretation pearls
○ Irregular hypoechoic lesion causing abrupt, segmental
loss of normal wall stratification
○ Extramural extension of tumor
○ Locoregional lymph node involvement
• Staging: CECT
• Metastases: Most commonly to regional lymph nodes, liver,
and lung
TOP DIFFERENTIAL DIAGNOSES
• Diverticulitis
• Inflammatory bowel disease
• Colonic lymphoma
KEY FACTS
• Gastrointestinal stromal tumors
• Intussusception
• Infectious colitis
• Ischemic colitis
CLINICAL ISSUES
• Most common signs and symptoms
○ Hematochezia
○ Altered bowel habit; abdominal pain
○ Weight loss
• Staged using AJCC TNM, Modified Astler Collier (MAC), or
Dukes staging systems
• 5-year survival: 50-60% depending on stage
DIAGNOSTIC CHECKLIST
• If colon cancer is detected sonographically, evaluate liver
for metastases at time of initial US scan
• Recommend CECT for complete staging
• Recommend colonoscopy for histologic confirmation
(Left) Graphic illustrates a
circumferential tumor ſt of
the colon with luminal
narrowing. Note "shouldering"
at both ends st. (Right)
Longitudinal ultrasound in a
patient with ascending colon
tumor shows asymmetrical
annular hypoechoic thickening
to a short segment of colon.
There is loss of colonic mural
stratification ſt, and
effacement of echogenic
lumen . Note "shouldering"
at the ends of the lesion st.
(Left) Sagittal CT reformat
from the same patient depicts
the ascending colon "apple
core" tumor ſt. Note
"shouldering" at both ends
and the luminal narrowing.
(Right) The terminal ileum ſt
and cecum from the same
patient proximal to the tumor
demonstrates mural edema
secondary to obstruction, but
note the preserved mural
stratification st.
674