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Table of Contents
Year : 2021  |  Volume : 4  |  Issue : 2  |  Page : 209-211

A rare case of rectal adenocarcinoma and small-bowel neuroendocrine tumor in a young patient with long-standing Crohn's disease: A case report

Department of Medicine, Division of Gastroenterology, King Saud University, Riyadh, Saudi Arabia

Date of Submission14-Sep-2020
Date of Decision13-Oct-2020
Date of Acceptance21-Oct-2020
Date of Web Publication13-Apr-2021

Correspondence Address:
Nahla Azzam
Department of Medicine, Division of Gastroenterology, King Saud University Medical City, King Saud University, Riyadh 12372
Saudi Arabia
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jnsm.jnsm_114_20

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Background: The association of adenocarcinoma of the colon and neuroendocrine tumor (NET) of the small bowel has been previously described in Crohn's disease (CD), however the concomitance of both neoplasms is extremely rare. Here, the author reports a rare case of both rectal adenocarcinoma and small-bowel NET in a young male with long-standing CD. Case Report: The patient presented with clinical and radiological features of intestinal obstruction 2 years posttotal colectomy and end ileostomy for rectal cancer and found to have ileal NET. Conclusion: Small-bowel NET symptoms can mimic CD and is a rare entity, but physicians should suspect NETs in CD patients presenting with intestinal obstruction.

Keywords: Colorectal cancer, Crohn's disease, neuroendocrine tumor

How to cite this article:
Azzam N. A rare case of rectal adenocarcinoma and small-bowel neuroendocrine tumor in a young patient with long-standing Crohn's disease: A case report. J Nat Sci Med 2021;4:209-11

How to cite this URL:
Azzam N. A rare case of rectal adenocarcinoma and small-bowel neuroendocrine tumor in a young patient with long-standing Crohn's disease: A case report. J Nat Sci Med [serial online] 2021 [cited 2021 Jun 13];4:209-11. Available from: https://www.jnsmonline.org/text.asp?2021/4/2/209/313638

  Introduction Top

The incidence of small-bowel malignancies has increased fourfold over the past decade.[1] Patients with Crohn's disease (CD) have an increased risk of developing small-bowel adenocarcinoma compared to the general population.[2] Furthermore, CD patients also carry a higher risk for other types of malignancies such as neuroendocrine tumors (NET).[3] The risk of NET in CD patients has been reported in literature as case reports or small cohort studies, and mostly detected coincidentally during surgery.[4] NET generally does not lead to symptoms until it causes partial obstruction, bleeding, or becomes metastatic.[5] A meta-analyses of cohort studies has shown increased risk of colorectal cancer (CRC) in patients with CD; it is assumed that chronic intestinal inflammation drives CRC.[6] The concomitant occurrence of both CRC and small-bowel NET in CD patients has never been described. Here, the author reports a rare case of concurrent ileal NET diagnosed 2 years after the diagnosis of rectal cancer in a young patient with long standing CD.

  Case Report Top

The patient is a 34-year-old Saudi male with a diagnosis of colonic CD since 2003. He was diagnosed based on the symptoms of bloody diarrhea, abdominal pain, and weight loss. He was initially treated with multiple courses of prednisolone, and then maintained on oral mesalamine 2.4 g daily and azathioprine 100 mg a day with poor compliance. Three years later, he started to have flare with recurrence of symptoms and developed perianal fistulae. He was started on anti-tumor necrosis factor (TNF) (infliximab) 5 mg/kg and received a total of 16 doses with good clinical response. He lost to follow-up for >8 years, and he stopped the medications by himself as he felt better till 2017. When he was admitted through emergency room with colonic obstruction, computed tomography (CT) scan of the abdomen and magnetic resonance imaging of the pelvis showed focal rectal wall thickening about 10 cm from the anal verge, highly worrisome for malignancy, and a left external iliac enlarged lymph node. Sigmoidoscopy showed sigmoid narrowing and ulcerated mass at the rectum 10 cm from the anal verge, and biopsy showed moderately differentiated adenocarcinoma of large bowel type, with the neoplastic glands invading the muscularis mucosa of the specimen [Figure 1]. His tumor stage was T3N1M0, so the patient received neoadjuvant chemoradiotherapy and then underwent total colectomy and end ileostomy. Six months later, endoscopy was performed through the stoma and showed normal-looking mucosa of the small bowel. Follow-up CT scan of the abdomen revealed no recurrence or distant metastasis with normal carcinoembryonic antigen (CEA). A year and half later, the patient started to have frequent obstructive symptoms which were managed conservatively. Two months later, he presented with severe abdominal pain, vomiting, decrease of stoma output, and weight loss. Abdominal examination revealed mild right lower quadrant (RLQ) tenderness without rigidity, guarding, or masses. Initial blood work showed hemoglobin of 13.7 g/dL, normal electrolyte and liver function tests, and C-reactive protein of 12.5. Abdominal CT demonstrated diffuse small-bowel dilatation reached up to 5 cm the dilatation started from the stoma site with no radiological signs of active CD. Endoscopy through the stoma showed ulcerated narrowed area 3 cm from ileostomy, biopsies were taken from the ulcerated mucosa and showed well differentiated NET Stage 1. The patient underwent laparoscopic small bowel resection, which revealed a distal small bowel narrowing with 2-cm small ulcerated lesion 5 cm distal to the stoma site which was resected. Small-bowel histology revealed findings of well-differentiated NET, Grade G2 [Figure 2]a and [Figure 2]b. The mitotic rate was 2 mitoses/2 mm2. The Ki67 index was 3%–5%. The tumor invades into muscularis propria, lymphovascular invasion, and perineural invasion were also present. The background of the small bowel showed focal minimal chronic active inflammation without transmural inflammation or granuloma. The postoperative course was uneventful, and the patient was referred to oncology for further workup to exclude distant metastasis.
Figure 1: Moderately differentiated adenocarcinoma of the rectum; the neoplastic glands invade the muscularis mucosa

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Figure 2: (a) Well-differentiated neuroendocrine tumor Stage 2. (b) Neuroendocrine tumor glands with strongly positive chromogranin stain

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  Discussion Top

Nearly 2% of all gastrointestinal cancers affect the small bowel, with the majority being adenocarcinoma. NETs of the small bowel are infrequently described in the setting of CD and are extremely rare, particularly in synchronous with adenocarcinoma of the colon.[2] The WHO revised the classification of small-bowel NETs in 2010 and all NETs are now considered potential malignant tumors under four grades based on mitotic and Ki67 index (%), and a new mixed adenocarcinoma/neuroendocrine carcinoma type has been added to the classification.[7] The crude incidence of gastrointestinal NETs has markedly increased over the past 20 years and is now estimated to be 5.25/100,000/year with a prevalence of 35/100,000/year.[7] NETs can demonstrate symptoms that mimic CD exacerbation, and both entities may be difficult to distinguish radiologically. The case reported here is a rare case of ileal NET diagnosed in a young patient with long-standing CD 2 years after the diagnosis and resection of rectal adenocarcinoma, which has never been published before. On reviewing the literature, five cases were identified of concurrent adenocarcinoma and carcinoid tumor of small bowel in patients with CD.[8] The authors postulated that the inflammation may cause hyperstimulation of enteroendocrine cells, leading to hyperplasia and then subsequently neoplasia. Sigel and Goldblum[9] reported the only series of colonic neuroendocrine neoplasms other than carcinoids arising in 14 patients with inflammatory bowel disease (IBD) (eight CD; six patients with ulcerative colitis). Six of the 14 neoplasms affected the rectum. Eleven cases out of the 14 were the authors suggested that neuroendocrine differentiation might have evolved from multipotential cells in the colonic dysplastic epithelium. This result was based on their findings of dysplasia in the adjacent mucosa in more than one-third of cases. The incidence of CRC in CD patients is 0.9–2.2 times higher than that of the general population. CD patients diagnosed with colon cancer at a younger age compared to their non-CD counterparts, and they often have a higher frequency of advance stages.[10] Similar observation has been reported in our patient. His risk for rectal cancer was most likely related to inflammation due to long disease duration >13 years and the extent of his colitis rather than related to anti-TNF therapy. He received infliximab for a short duration and CRC was diagnosed >8 years postcessation of the therapy. Of note, a meta-analysis looked at the data from controlled trials of infliximab therapy for CD, in which the incidence of cancer of any type was found to be similar in patients treated with infliximab and those who received placebo.[11]

  Conclusion Top

The concomitant presence of both CRC and small-bowel NET is extremely rare. The case reported here is the first of its kind in literature, who developed both tumors 2 years apart. Small-bowel NET should be suspected in CD patients with obstructive symptoms.


Informed consent was obtained from the patient for publication of this report and any accompanying images.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understands that his name and initial will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Yao JC, Hassan M, Phan A, Dagohoy C, Leary C, Mares JE, et al. One hundred years after “carcinoid”: Epidemiology of and prognostic factors for neuroendocrine tumors in 35,825 cases in the United States. J Clin Oncol 2008;26:3063-72.  Back to cited text no. 1
Aparicio T, Zaanan A, Svrcek M, Laurent-Puig P, Carrere N, Manfredi S, et al. Small bowel adenocarcinoma: Epidemiology, risk factors, diagnosis and treatment. Dig Liver Dis 2014;46:97-104.  Back to cited text no. 2
Algaba A, Guerra I, Castaño A, de la Poza G, Castellano VM, López M, et al. Risk of cancer, with special reference to extra-intestinal malignancies, in patients with inflammatory bowel disease. World J Gastroenterol 2013;19:9359-65.  Back to cited text no. 3
Norlén O, Stålberg P, Öberg K, Eriksson J, Hedberg J, Hessman O, et al. Long-term results of surgery for small intestinal neuroendocrine tumors at a tertiary referral center. World J Surg 2012;36:1419-31.  Back to cited text no. 4
Dahdaleh FS, Calva-Cerqueira D, Carr JC, Liao J, Mezhir JJ, O'Dorisio TM, et al. Comparison of clinicopathologic factors in 122 patients with resected pancreatic and ileal neuroendocrine tumors from a single institution. Ann Surg Oncol 2012;19:966-72.  Back to cited text no. 5
Jess T, Gamborg M, Matzen P, Munkholm P, Sørensen TI. Increased risk of intestinal cancer in Crohn's disease: A meta-analysis of population-based cohort studies. Am J Gastroenterol 2005;100:2724-9.  Back to cited text no. 6
Pavel M, Öberg K, Falconi M, Krenning EP, Sundin A, Perren A, et al. ESMO Guidelines Committee Gastroenteropancreatic neuroendocrine neoplasms: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up. Ann Oncol 2020;31:844-60.  Back to cited text no. 7
Boltin D, Levi Z, Halpern M, Fraser GM. Concurrent small bowel adenocarcinoma and carcinoid tumor in Crohn's disease – Case report and literature review. J Crohns Colitis 2011;5:461-4.  Back to cited text no. 8
Sigel JE, Goldblum JR. Neuroendocrine neoplasms arising in inflammatory bowel disease: A report of 14 cases. Mod Pathol 1998;11:537-42.  Back to cited text no. 9
Hrabe JE, Byrn JC, Button AM, Zamba GK, Kapadia MR, Mezhir JJ, et al. A matched case-control study of IBD-associated colorectal cancer: IBD portends worse outcome. J Surg Oncol 2014;109:117-21.  Back to cited text no. 10
Peyrin-Biroulet L, Deltenre P, de Suray N, Branche J, Sandborn WJ, Colombel JF, et al. Efficacy and safety of tumor necrosis factor antagonists in Crohn's disease: Meta-analysis of placebo-controlled trials. Clin Gastroenterol Hepatol 2008;6:644-53.  Back to cited text no. 11


  [Figure 1], [Figure 2]


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