What is the role of imaging studies in the workup of pediatric colorectal tumors?

Updated: Jun 06, 2020
  • Author: Jaime Shalkow, MD, FACS; Chief Editor: Cameron K Tebbi, MD  more...
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Conventional radiographic studies include barium enema with air contrast to define the tumor. Abdominal and chest computed tomography (CT) scans define spread to the liver, lungs, or enlarged lymph nodes, as well as pelvic metastases, especially to the ovaries. Colorectal cancer has the ability to metastasize through various routes, including transmural invasion and spread by continuity, intraluminal extension, and hematogenous, lymphatic, and transperitoneal routes. Kaste et al analyzed 32 patients with peritoneal metastatic implants from different primary tumors and found that 22% of these patients had colorectal cancer. [62]

CT scanning may be unable to detect intra-abdominal metastases because of lesion size, paucity of intra-abdominal fat, contiguity with the primary tumor, ascites, implant location, and adequacy of bowel opacification. Current CT scanners are able to detect implants as small as 5 mm in diameter. Magnetic resonance imaging (MRI) may further improve detection.

Colonoscopy is useful in locating the site of lesions within the large bowel. The entire length of the colon should be evaluated. Transrectal ultrasonography may help determine the extent of invasion and resectability of rectosigmoid cancer. Intraoperative ultrasonography of the liver may reveal metastases not observed in other imaging studies. [12] Radioisotope studies should include a bone scan; if the results are positive, bone marrow aspiration and biopsy are indicated to determine spread to the marrow.

Advanced imaging techniques are indicated for specific patient groups. The European Society of Gastrointestinal Endoscopy (ESGE) strongly recommends that conventional screening with white light colonoscopy in high-risk patients should be performed, as well as pancolonic conventional or virtual chromoendoscopy for patients suspected or known to have Lynch syndrome or serrated polyposis syndrome.

The ESGE also recommends that all patients with longstanding colitis undergo periodic pancolonic chromoendoscopies, with either 0.1% methylene blue or 0.1% to 0.5% indigo carmine and targeted biopsies, replacing the common practice of non-targeted 4-quadrant biopsies. [11]

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