Familial adenomatous polyposis (FAP) is a known risk factor for colonic and extracolonic malignancies. Patients with this autosomaldominant disease develop hundreds to thousands of colon and rectal adenomas during their second decade of life, most frequently due to a mutation on the adenomatous polyposis coli (APC) gene.1 Most patients with FAP have a significant family history of colorectal cancer; however, around 25–30% have no known family history of the disease. Today, most patients with FAP undergo prophylactic proctocolectomy at an early age and require monitoring for other extracolonic manifestations of the disease such as duodenal carcinoma.
We report a case of a 70 year-old male with a history of prophylactic proctocolectomy 48 years prior to development of FAP, and subsequent pancreaticoduodenectomy for duodenal adenomatous changes. The patient presented with an adenocarcinoma of the ileostomy and underwent successful en bloc resection of the ileostomy site and terminal ileum.
A 70 year-old male presented with a rapidly enlarging lesion at the end ileostomy (Figure 1). Biopsy in the office was positive for adenocarcinoma arising within a tubulovillous adenoma. He had a history of FAP managed with a proctocolectomy 48 years prior, transduodenal excision of polyps 22 years ago, and a pancreaticoduodenectomy 3 years prior to the current presentation for adenomatous changes at the ampulla of Vater. His last surveillance esophagogastroduodenoscopy (EGD) six months ago was unremarkable, but no recent ileoscopy had been performed.
The patient was asymptomatic at presentation. Basic lab work and carcinoembryonic antigen were within normal limits. Preoperative chest, abdomen, and pelvis computed tomography (CT) showed no signs of metastatic disease. A preoperative EGD and ileoscopy identified several gastric polyps and multiple polyps in the ileum. The largest ileal polyp was 6 mm with tubular histology and high-grade dysplasia. No Spigelman score can be given due to the patient’s previous pancreaticoduodenectomy.
En bloc resection of the ileostomy site, terminal ileum, and mesentery with reformation of an end ileostomy was performed (Figure 2). Final pathology demonstrated a well-differentiated adenocarcinoma arising from a tubulovillous adenoma with invasion into but not through the muscularis mucosa T1N0M0 (Figure 3). The surgical margins were free of tumor. Postoperative recovery was uneventful with no short-term recurrence, but the patient died within one year due to cardiac disease.
FAP is seen in 3–10 patients per 100,000 and affects men and women equally.1 It is a well-known risk factor for colon and rectal malignancies, which can develop a decade after polyps form, but less than 1% of all colorectal cancers are attributable to FAP. Genetic testing in patients suspected of FAP includes both APC and MUTYH genes, and prophylactic colorectal surgery is recommended in the late teens to early twenties.
Lifelong monitoring for extracolonic malignancies is necessary due to a 4–12% lifetime risk of developing duodenal cancer, 2% risk of medulloblastoma, 2% risk of papillary carcinoma of the thyroid, 1–2% risk of hepatoblastoma, and less than 1% risk of gastric or pancreatic cancers.2 Patients need upper endoscopy surveillance starting in their late teens to early twenties. Currently, there is insufficient high-level evidence to support routine small bowel screening distal to the duodenum. CT enterography or magnetic resonance imaging can be used for small bowel visualization especially in the setting of advanced duodenal polyposis. Additionally, inspection of the ileostomy and ileoscopy can be considered every 1–3 years.2 There are no official recommendations regarding capsule endoscopy, but it may be a useful tool in screening FAP patients due to their risk of distal small bowel adenomas.3
Adenocarcinoma of the ileostomy site is an uncommon sequela seen in patients with FAP, ulcerative colitis, and Crohn’s disease. Reported cases of any ileostomy malignancy occur a median of 25 years but have also been described within five years after its creation.4,5 There is a higher incidence of adenocarcinoma in ileostomies ranging from two to four per 1,000 patients compared to approximately seven per 1,000,000 developing small bowel malignancy.6 The etiology of this disease is still under speculation, but a likely mechanism is a combination of chronic inflammation and cell proliferation at the border of the skin and mucosa, leading to metaplasia.4,7 Common presenting symptoms include bleeding, bowel obstruction, or stoma appliance difficulties, but patients may be asymptomatic. Regular ileostomy examination with the stoma appliance removed is the most important tool for early diagnosis. The differential diagnoses for ileostomy abnormalities include carcinoma and benign adenomatous and hyperplastic polyps.
There are currently no accepted guidelines for management of small bowel or ileostomy site adenocarcinoma, but aggressive treatment offers a good prognosis.8 If a lesion is seen at the ileostomy site, biopsy can be safely completed during an outpatient clinic visit. After confirmation of carcinoma, staging with CT and endoscopy should be performed. Of note, metastatic disease to the lymph nodes was only reported in patients with the primary tumor size over 4 cm. Surgical management consists of en bloc resection of the ileum and ileostomy site and its recreation either locally or via laparotomy. At least 85% survival can be achieved with surgical treatment.8
Adenocarcinoma of the ileostomy site is a rare pathology that deserves consideration, especially in patients with a history of FAP or inflammatory bowel disease. We recommend that a thorough examination of the ileostomy be performed at the time of EGD surveillance. When suspected, biopsy of the ileostomy site lesion is required, and if it demonstrates adenocarcinoma, surgical evaluation, cancer staging, and resection are necessary. For tumors under 4 cm, local en bloc resection avoids the morbidity of a laparotomy.
We would like to thank Paul Casella, MFA, Office of Faculty Affairs and Development, University of Iowa Carver College of Medicine for editorial assistance.
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2. National Comprehensive Cancer Network. Genetic/Familial High-Risk Assessment: Colorectal (Version 3.2019). https:// www.nccn.org/professionals/physician_gls/pdf/genetics_ colon.pdf. Accessed December 30, 2019.
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