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ACG Case Rep J
ACG Case Rep J
ACGCRJ
AC9
ACG Case Reports Journal
2326-3253
Wolters Kluwer Maryland, MD

ACGCR-24-0585
10.14309/crj.0000000000001487
00025
3
Case Report
Small Bowel
An Extremely Rare Presentation of Mucinous Adenocarcinoma Originating From Meckel Diverticulum Masquerading in a Young Woman With Crohn's Disease
Fawaris Nada MBBCh, MRCP 1
Shariq Sohail MBBS, FRCP 1s.shariq@nhs.net

Elnaggar Mohamed MD, MRCP 1m.el-naggar@nhs.net

Kubba Faris FRCSI, FRCPath 1faris.kubba@nhs.net

Haria Rashmi MBBS, MSc, FrcPath 2r.haria@nhs.net

1 Ealing Hospital, London Northwest University Healthcare NHS Trust, London, UK
2 St. Mark's Hospitals, London Northwest University Healthcare NHS Trust, London, UK
Correspondence: Nada Fawaris, MBBCh, MRCP (nada.fawaris@nhs.net).
9 2024
12 9 2024
11 9 e0148723 6 2024
27 7 2024
© 2024 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of The American College of Gastroenterology.
2024
https://creativecommons.org/licenses/by-nc-nd/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal.

ABSTRACT

Mucinous adenocarcinoma with signet cell features originating from Meckel diverticulum (MD) is an extremely rare primary malignant tumor. A woman in her 30s presented with multiple episodes of vomiting, abdominal pain, and constipation. She had a history of stricturing Crohn's disease and managed well with steroids, azathioprine, and infliximab. This time, a computed tomography scan showed distal ileal small-bowel obstruction. Urgent surgery for a nonsettling small bowel obstruction was performed. MD was incidentally found and was concerning for malignancy. This case report illustrates how this extremely rare malignancy was behaving like Crohn's disease, which delayed the diagnosis and treatment.

KEYWORDS:

Meckel diverticulum
adenocarcinoma
signet ring cell
Crohn's disease
OPEN-ACCESSTRUE
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pmcINTRODUCTION

Meckel diverticulum (MD) is the most common congenital anomaly of the small bowel. It is a true diverticulum of the small intestines, typically found within 100 cm proximal to the ileocecal valve. It is a result of incomplete obliteration of the vitelline omphalomesenteric duct in the developing embryo.1 It affects ∼2% of the population. It is estimated that ∼4% of those who have MD will present with symptoms or develop a complication. MD may present as intestinal obstruction (36.5%), intussusception (13.7%), inflammation (12.7%) and hemorrhage (11.8%). Among the symptomatic patients, nearly 3.2% have a tumor in the MD of which most are benign. The predominant types of MD malignant tumors in order of prevalence are neuroendocrine tumors, gastrointestinal stromal tumors, adenocarcinomas, metastases, and lymphomas 2

CASE REPORT

A young lady in her 30s, known to have ilio-cecal Crohn's disease, was diagnosed 3 years ago by histopathology which showed chronic moderate active minimally crypt destructive colitis involving right colon and areas of histiocytic granulomas in ileocecal valve (Figure 1). This colitis settled on steroids, azathioprine, and infliximab. She presented with generalized abdominal pain and multiple episodes of vomiting, bloating, and constipation for 3 days. She had a new small bowel stricturing disease with 4 episodes of obstruction in 2 months, the latest bringing her to the hospital a month ago, settled on accelerated infliximab. This time she came back with generalized abdominal pain, persistent vomiting, bloating, and constipation for 3 days. The abdomen was soft and generally tender, bowel sounds were present. The rectum was empty by digital rectal examination, and serum lactate was 0.7 mmol/L. The clinical picture was suggestive of a possible bowel obstruction. Abdominal and pelvic computed tomography (CT) with contrast showed small bowel obstruction involving the distal ileal loops secondary to tight stricture at the distal third of the ileum (Figure 2). A repeat CT of the abdomen and pelvis 10 days later showed the same findings. She was reviewed by the surgical team and treated jointly with the gastroenterology team for a presumed small bowel obstruction while arranging for an urgent stricturoplasty. In the meantime, she was reviewed by the nutrition team and commenced on parenteral nutrition. An emergency laparotomy was done for presumed nonsettling small bowel obstruction in the context of Crohn's disease. Intraoperatively, MD was found at the transition point, hard and craggy in consistency, with multiple mesenteric nodules found concerning for malignancy (Figure 3). There were also multiple dilated small bowel loops with serous peritoneal fluid found, mesenteric biopsies taken, and end-to-end anastomosis completed. There was no evidence of macroscopic Crohn's disease in the small intestine. She remained inpatient for 5 weeks, received 1-week course of antibiotics for delayed wound healing and infection. Histopathology of the MD obstructing lesion confirmed the diagnosis of poorly differentiated adenocarcinoma, a mucinous subtype with signet ring cell features (Figure 4). There was serosal surface breach with extensive extramural venous and perineural invasion. Mismatch repair immunohistochemical stains showed normal expression, Cytokeratin 7 and 20, Caudal type homeobox 2 were positive. Neuroendocrine markers were negative. The mesenteric cut margin was affected by the tumor (R1), and the longitudinal small bowel margins were clear. A peritoneal nodule showed metastatic adenocarcinoma, a mucinous subtype with signet ring cells. A staging CT scan was negative for metastasis. Patient received adjuvant chemotherapy and 3 cycles of the folinic acid, fluorouracil and oxaliplatin course of 2 chemotherapy agents for 6 months. Inflammatory bowel disease team recommended stopping azathioprine and reassessing Crohn's disease after chemotherapy was completed. Another month later, she came back to the hospital with bowel symptoms. A abdominal and pelvic CT showed long segment of profoundly ischemic small bowel (Figure 5). She underwent an emergency laparotomy which resulted in further resection of 150 cm of the small bowel. Histology showed ischemic necrosis (Figure 6). This was likely secondary to adhesions from chemotherapy; therefore, chemotherapy was converted to palliative chemotherapy, and she received 6 cycles of folinic acid, fluorouracil, and irinotecan chemotherapy + cetuximab. She was readmitted 2 months later with presumed recurrent small bowel obstruction. Abdominal and pelvic CT with contrast showed dilated bowel loops with some hold-ups proximally. The bowel loops looked slightly thickened, but there was no recurrent disease. She was managed conservatively. She was readmitted 5 months later with chest sepsis, which required intensive care unit admission for inotropic support. Unfortunately, she deteriorated and was no longer eligible for cardiopulmonary resuscitation or intensive care unit, she was palliated and sadly died.

Figure 1. Photomicrographs (highlighted hematoxylin and eosin 100×) confirm active chronic colitis with areas of histiocytic granulomas in ileocecal valve.

Figure 2. An abdominal and pelvic computed tomography scan, an arrow pointing toward tight stricture at the distal end of the ileum causing small bowel obstruction involving the distal ileal loops.

Figure 3. Macroimages of the resected Meckel diverticulum.

Figure 4. Composite image (hematoxylin and eosin 20×) of the mucinous adenocarcinoma within the Meckel diverticulum with signet cell features.

Figure 5. An abdominal and pelvic computed tomography scan showing long segment of profoundly ischemic small bowel appears related to “swirled” central mesentery.

Figure 6. Photomicrograph (hematoxylin and eosin 20×) showing the necrotic small bowl.

DISCUSSION

Approximately 3.2% of individuals with symptomatic MD have an MD tumor, the majority of which are benign. Malignant transformation has been reported in 0.5%–3.2% of all reported cases. Among these malignant MD tumors are carcinoids (84.6%), gastrointestinal stromal tumors (8.0%), and adenocarcinomas which account for less than 6.0%, making it an extremely rare malignancy.3 According to a study performed by Mayo clinic, the data showed that up to 89.5% of the 402 cases of MD malignant tumors were discovered incidentally. There was a higher incidence in men with 261 men compared with 118 women. Median age was 58. Among these 402 cases, only 24 were adenocarcinomas, however, without further specification of the histological features of the tumor either gastric or intestinal in nature. At the time of diagnosis, 104 patients had metastatic cancer. We could find only 3 cases of signet ring adenocarcinoma originating from MD in the literature making it an extremely rare tumor with poor prognosis.4 Unfortunately, malignant tumors of MD can be asymptomatic or present with vague symptoms; however, acute symptoms including gastrointestinal bleeding, perforation, or chronic symptoms such as intestinal obstruction, anemia, or unintentional weight loss can be suggestive of malignant tumors of the MD or they can be masked by another gastrointestinal disease, such as Crohn's disease, as in our case report. Therefore, in patients with a known chronic gastrointestinal disease, we recommend exploring other causes, including malignancy, especially if the patient presents with recurrent episodes of small bowel obstruction and does not appear to respond to conventional treatments for Crohn's disease.

DISCLOSURES

Author contributions: N. Fawaris wrote the manuscript and reviewed the literature. M. Elnaggar was the treating consultant and reviewed the manuscript. S. Shariq reviewed and edited the manuscript. R. Haria diagnosed the adenocarcinoma with signet ring features and provided macroimages of Meckel diverticulum. F. Kubba reported Crohn's disease slides and provided all histopathology slides. N. Fawaris is the article guarantor.

Financial disclosure: None to report.

Informed consent was obtained for this case report.
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