P0615 - Colon Adenocarcinoma Metastasis Through Ileocolic Fistula to Small Bowel in the Setting of Crohn’s Disease

Michael Tseng, MD¹, Taseen Syed, MBBS, MD¹, Patricija Zot, MD², Ravi Vachhani, MD^2
1Virginia Commonwealth University Health Systems, Richmond, VA; ²Virginia Commonwealth University, Richmond, VA

Introduction: Patients with Crohn’s disease (CD) are at higher risk of developing colorectal cancer (CRC) and gastrointestinal fistula. We report an unusual case of sigmoid colon adenocarcinoma in a CD patient that metastasized to the ileum through an ileocolic fistula tract.

Case Description/Methods: A 37-year-old Caucasian male with a history of ileocolic CD presented with abdominal pain associated with vomiting, and diarrhea. The patient was diagnosed with CD at the age 19 but was not on treatment due to non-compliance. Computed tomography of the abdomen revealed prominent wall thickening of the terminal ileum consistent with active inflammation suggestive of CD flare with a fistulous tract noted between the terminal ileum and sigmoid colon. (Figure 1) The patient was started on budesonide with a plan to start infliximab as an outpatient for fistulizing CD. Colonoscopy before initiating infliximab, showed a severe rectosigmoid stricture that could not be traversed. (Figure 2) Biopsies from the stricture revealed adenocarcinoma of the colon. The patient underwent open total proctocolectomy; however, at the time of surgery, there was involvement of the terminal ileum through the sigmoid colon-ileum fistulous tract, and therefore, a proximal portion of the terminal ileum was also surgically resected. The pathology showed adenocarcinoma of the sigmoid colon with the involvement of the terminal ileum at the fistula site. (Figure 3) The patient recovered well from surgery and is currently undergoing adjuvant chemotherapy.

Discussion: Metastatic CRC through a fistula is a very rare disease presentation with no reports in the literature of implantation into the small bowel through an ileal-sigmoid fistulous tract. CD is associated with a higher risk of fistula development, with occurrence reported in 17-50%. Common metastatic sites of colon cancer include the liver, lungs, nervous system, and peritoneum. Few cases in the past described CRC metastasized within the gastrointestinal tract through a fistula; these metastatic events are almost always through an anal fistula or closer proximity anatomical position. (Table 1) Intriguingly in our case, sigmoid adenocarcinoma developed and further metastasized to the ileum via the ileal-sigmoid fistula in the setting of CD. In addition to presenting a unique pathological phenomenon in these patients, this case raises awareness of the importance of regular follow-up and early initiation of IBD therapies.


Figure: Figure 1: CT of abdomen: thickened terminal ileum immediately adjacent to the sigmoid colon with no clear fat plane between bowel loops, which represents a fistula formation.

Figure 2: Colonoscopy: Stricture at distal sigmoid colon unable to traverse with colonoscope

Figure 3: Gross specimen included a portion of terminal ileum, an attached appendix, colon, rectum and anus. On the serosal surface, a fistula was identified at the ileocecal valve. The specimen was opened to reveal a 3.0 x 3.0 cm ulcerated concentric mass (asterisk) with a central area of tan-gray necrosis.

Figure 4: Moderately differentiated adenocarcinoma with mucinous features (the same morphology as in the sigmoid colon specimen) is found in the adjacent terminal ileum (normal ileum mucosa shown by arrow) at the site of fistula (asterisk).

Author	Age, Sex	IBD (Yes/No), type	Primary cancer site	Metastatic site	Fistula (Yes/No)	Cancer implanted fistula (Yes/No)
Ikeda	68, Male	No	Rectosigmoid adenocarcinoma	Anal fistula/Anus	Yes, Anal fistula	Yes
Benjelluon	55, Male	Yes, unspecified	Rectosigmoid adenocarcinoma	Anal sphincter/perianal area	Yes, Anal fistula	Yes
Benjelluon	68, Male	No	Rectosigmoid adenocarcinoma	Perianal mass	Yes, perineal fistula	Yes
Gomes	65, Male	No	Sigmoid adenocarcinoma	Anus	Yes, Anal fistula	Yes
Spiridaki	79, Male	No	Mucinous rectosigmoid adenocarcinoma	Anus	Yes, Anal fistula	Yes
Balcabasa	61	No	Synchronous adenocarcinoma	Lymph	Yes, Gastrocolic fistula	No
Zhou	59, Male	No	Colon tubular adenocarcinoma	Gastral antral fistula; omentum, lymph node, serosa.	Yes, Gastrocolic fistula	Yes
Lee	82, Female	No	Gastric carcinoma	Colon at splenic flexture	Yes, Gastrocolic fistula	Yes
Tejedor	49, Male	No	Colon carcinoma	Stomach, jejunum	Yes, Gastrojejunocolic fistula	Yes
Nakazawa	84, Male	No	Sigmoid colon cancer	Bladder, Urethral	Yes, Colovesical fistula	Yes
Present Case	37, Male	Yes, CD	Sigmoid colon cancer	Ileum	Yes, Ileosigmoloid fistula	Yes

* IBD; inflammatory bowel disease

Table: Table 1. Cases of colon cancer metastasis to other sites in the gastrointestinal tract through fistulous tracts


Disclosures:
Michael Tseng indicated no relevant financial relationships.
Taseen Syed indicated no relevant financial relationships.
Patricija Zot indicated no relevant financial relationships.
Ravi Vachhani indicated no relevant financial relationships.


Michael Tseng, MD¹, Taseen Syed, MBBS, MD¹, Patricija Zot, MD², Ravi Vachhani, MD². P0615 - Colon Adenocarcinoma Metastasis Through Ileocolic Fistula to Small Bowel in the Setting of Crohn’s Disease, ACG 2021 Annual Scientific Meeting Abstracts. Las Vegas, Nevada: American College of Gastroenterology.