A 63-year-old Japanese man with no symptoms had a positive fecal occult blood test. His past medical history included a duodenal ulcer at 50 years of age.
The colonoscopy revealed, in the observation range, many scars caused by inflammation in the cecum and ascending colon, an intestinal stricture caused by inflammatory polyps in the transverse colon (Figure 1A-D), loss of both visible vascular patterns and haustra in the descending colon (Figure 1E), and normal mucosa in the sigmoid colon (Figure 1F), rectum, and ileum. Examination of biopsies from each segment of colon (including even specimens from normal mucosa) revealed chronic colitis accompanied by IS, as evidenced by basophilic fringes on the luminal surface of the intestinal mucosa and infiltration of lymphocytes and eosinophils in subepithelial lesions (Figure 2A). There were no obvious dysplastic changes (Figure 2B). Abdominal computed tomography (CT) revealed wall thickening in the transverse colon around the hepatic flexure (Figure 3A). The upper endoscopy and enteroscopy findings were within normal limits. Laboratory data, including carcinoembryonic antigen, carbohydrate antigen 19-9, interferon-gamma release assay (IGRA), purified protein derivative skin test, Entamoeba histolytica antibody, human immunodeficiency virus antibody, and fecal examinations, including culture and polymerase chain reaction for Mycobacterium tuberculosis, revealed no remarkable findings. Hence, his condition was diagnosed as chronic colitis associated with IS. Metronidazole (MNZ) 1500 mg/d for 14 days was initiated to treat the IS. Although spirochetes were eliminated in pathological examinations, MNZ was not effective for the intestinal stricture of the transverse colon. We performed colonoscopy 4 times for 20 months since the fecal occult blood test was positive and each biopsy indicated colitis but no obvious malignancy (Figure 2C, Table 1).
The patient was admitted to our hospital with an acute abdomen 20 months after the initial presentation. He had urgent abdominal pain, constipation, and fever. Abdominal CT revealed exacerbation of the intestinal stricture in the transverse colon around the hepatic flexure (Figure 3B) and dilatation of the ascending colon with extraintestinal fluid (Figure 3C). We strongly suspected intestinal perforation due to obstruction. Subtotal colectomy and ileostomy were performed and the symptoms resolved. Histopathological examination of the specimens revealed MC that had infiltrated into the muscularis propia and subserous layers of the visceral peritoneum, purulent peritonitis due to perforation within the tumor and lymph node metastasis (Figure 4). The final histopathological diagnosis was a pT4a (invasion of serosa of peritoneum), pN1 (1/12), Ly0, V0, M0, and R0 tumor, corresponding to the Union for International Cancer Control IIIB classification. An immunohistochemical stain for DNA MMR proteins, including MLH1, MSH2, PMS2, and MSH6, revealed no lack of these expressions (Figure 5). Intensified adjuvant chemotherapy according to the Xeloda (capecitabine) and oxaliplatin schema was initiated. Currently, after 14 months of follow-up, the patient is without detectable tumor recurrence, as shown by abdominal CT scan and ultrasound examination (Table 1).