Crohn’s disease manifesting as ileo-urachal fistula: Two cases reports and review of literatures

Highlights • Urachal tumor or umbilical discharge in Crohn’s disease are examined for internal fistula from diseased ileum to urachus.• En broc resection with intestinal lesion and urachus is performed with successful outcome.• Partial cystectomy is sometimes performed with urinary bladder inflamed.


Introduction
Crohn's disease usually manifests as urinary complications, including fistulas. When a fistula develops near the umbilicus, a tract or inflammation can potentially form remnant embryonic structures, including a patent urachus. There are few reports in the global medical literature on a fistula involving a patent urachus in a patient with Crohn's disease [1]. Here, we report ileourachal fistula formation in two patients with Crohn's disease and describe the clinical features, treatments,and outcomes of these partients. The finding have been reported in line with the PROCESS criteria [2].

Case 1
A 29-year-old man with Crohn's disease and ileitis experienced upper abdominal pain. A small bowel series identified a longitudinal ulcer and subsequent abdominal computed tomography (CT) showed an ileal stricture and an urachal tumor mass that extended into the umbilicus (Fig. 1a, b). He was referred to our hospital for surgery because of a fistula from the stenotic ileum to the urachal tumor. Intraoperatively, it was found that the urachal remnant connected to the urinary bladder (Fig. 2a, b), and the Crohn's disease-related intestinal lesion had formed a fistula to the urachus. The patieint underwent a partial ileal resection, urachal resection, and partial cystectomy (Fig. 3a-c). There were noncaseating epithelioid granulomas in the muscularis propria of the small intestine with inflammation of all layers, and these findings are characteristic of Crohn's disease. There was extensive neutrophil infiltration and inflammation beneath the epithelium of the urachus because of exposure to foreign substances (Fig. 4a, b). The patient had an uneventful recovery and was healthy with no recurrence at 8 years of follow-up.

Case 2
A 43-year-old man was diagnosed with Crohn's disease and ileitis when he was at 33 years of age. At 41 years of age, he experienced fecal discharge from his umbilicus, pneumaturia, and fecaluria with frequent urination. A small bowel series and barium enema study showed an ileal stricture, and an ileorectal fistula. The patient was referred to our institute for surgery at 43 years of age. A small bowel series showed an ileal lesion with a fistula to the rectum and cecum, but not to the umbilicus. Abdominal CT indicated an ileal lesion involving the urachus, with abscess formation. Because the patient had severe pain, cystoscopy could not be performed. Intraoperatively, it was found that the patient had a periumbilical inflammatory lesion extending to the bladder through the urachal remnant and the longitudinal ulcer of the ileal lesion ( Fig. 5a, b). The patient underwent urachal curettage, partial ileal resection, and partial cystectomy. The patient showed severe inflammation of the bladder, a decreased bladder capacity of 150 ml after the cystectomy, and frequent urination. He was administered infliximab after the surgery and was free of recurrence at 6 years of follow-up.

Discussion
The urachus is derived from the endoderm, and it extends upward from the top of the fetal bladder. The urachal lumen typically closes after approximately 5 months of gestation. The incidence of incomplete obliteration to has been reported be 1 in 5000, and it leads to an anatomical abnormality [3]. Internal fistulization is a common complication of Crohn's disease. Internal fistulas form between adjacent bowel loops or between the bowel and bladder or vagina [4]. These fistulous tracts occur secondary to transmural inflammation and abscess formation. Among all the fistulas to the urinary system in Crohn's disease, enterovesical fistulas represent 8-12% of internal fistulas, while enterourachocutaneous fistulas represent 0.6-1% only of these fistulas [4]. In Crohn's disease, enterourachal fistula formation involves the spread of the fistula to the urachus through the bladder [5] and subsequent spread of spontaneous umbilical fistulization along the course of a persistent urachal remnant [1,4,5].
Patients with an ileourachal fistula have a history of pneumaturia, fecaluria, umbilical drainage from the umbilicus, and cystitis symptoms [5]. The diagnostic work-up in these patients should include ultrasound, CT, MRI, cystoscopy, a small bowel series, fis-  tulography, or a barium enema study [4,5]. In particular, CT reveals the form of the soft tissue mass like cyst from the umbilicus to the apex of the bladder, and recognition of the effect of the wall with enhancement [3]. There are few reported cases of an enterourachal fistula diagnosed with a small bowel series, fistulography, and a barium enema study [1,5]. Many authors have reported that the initial diagnosis was confirmed during exploratory surgery [3,[5][6][7]. Additionally, it has been mentioned that nutritional support or medical therapy is important in the treatment of an enterourachocutaneous fistula [7].
In many of these cases, urachal resection and partial cystectomy with intestinal resection are performed. Urachal resection is generally recommended because there is a 30% chance of urachus reinfection and because the urachal sinus has malignant potential [8]. Several authors have suggested that primary urachal adenocarcinoma may result from either embryonic metaplasia of the transitional cell lining or inclusion of the colonic mucosa [3]. Sur-gical excision of an enterourachal fistula is considered as one treatment options.
Seventeen cases have been reported globally, including our cases (Table 1) [1,[3][4][5][6][7][8][9][10][11]. There was only three reported cases only of pyourachus in patients with Crohn's disease in Japan [11], including both of our cases. Fourteen cases had an ileal lesion. Ileal resection was performed in all cases, except one of our cases. One urachal cyst was ablated, and one case was treated with medical therapy alone. There was no experienced recurrence of the urachal lesion.

Conclusion
In cases of Crohn's disease with an enterocutaneous fistula or pus discharge via the umbilicus an examination to detect an urachal remnant with a fistula from the diseased intestine should be performed. En bloc resection of the urachal remnant and intestinal  lesion is a viable surgical treatment option if an urachal remnant and intestinal lesion are identified.

Conflicts of interest
The authors declare no conflicts of interest associated with this manuscript.

Funding source
None of the authors has any conflicts of interest or any financial ties to disclose.

Ethical approval
We have a consent by the patient. Ethical approval was obtained from the ethical committee of Hiroshima University Hospital.

Consent
Written informed consent was obtained from the patients for the publication of this case report and any accompanying images. A copy of the written informed consent is available for review by the Editor-in-Chief of this journal.

Author contribution
HY and KT wrote the manuscript. KT, RH, YS and HO performed the operation. HY and KT performed the research/study, analyzed the data, designed the study, and interpreted the results. All authors conceived the study, participated in its design and coordination, and helped draft the manuscript. All authors read and approved the final manuscript.

Registration of research studies
We have registered for Research Registry. (UIN:researchregistry4274).

Provenance and peer review
Not commissioned, externally peer reviewed.