Case Report

A 58-year-old healthy man with no family history of colorectal cancer or inflammatory bowel disease presented to our colorectal clinic with a 6-month history of bilateral lower abdominal pain radiating to the back, 5-pound weight loss, and irregular watery bowel movements. He has one alcoholic drink per day and denied tobacco and recreational drug use. There was no nausea, vomiting, melena, hematochezia, shortness of breath, chest pain, dysuria or previous abdominal surgeries. On presentation his vitals were normal. Physical exam revealed no abdominal tenderness, distention, or palpable masses.DiagnosisPrior to the colorectal surgery clinic visit, a stool DNA test was ordered by his primary care physician and was negative. Laboratory studies were remarkable only for a carcinoembryonic antigen (CEA) level of 5.9 ng/mL He was initially diagnosed with irritable bowel syndrome. Colonoscopy performed by the gastroenterologist revealed a long rectosigmoid stricture that required a gastroscope to negotiate. The cecum and appendiceal orifice appeared normal. Biopsies of the rectosigmoid stenosis showed no significant pathologic abnormality and was non-diagnostic. Computed tomography (CT) imaging of the abdomen and pelvis demonstrated an irregular rim-enhancing heterogeneous mass measuring 6.7 cm x 2.8cm, originating from the base of the cecum and extending across the midline and tethered to the rectosigmoid junction without evidence of fistula (Figure 1). CT-guided fine needle aspiration was unsuccessful. The patient was then referred to the colorectal surgery clinic for further evaluation.Differential DiagnosisConsidering patient symptoms, CT imaging, and endoscopic findings, the differential diagnosis included possible colorectal malignancy, perforated appendix with pelvic abscess formation with involvement of the rectosigmoid junction, perforated colon cancer with abscess formation, or inflammatory bowel disease with fistula and abscess formation.TreatmentThe patient underwent an exploratory laparotomy for concern of possible malignancy and near- obstructing rectosigmoid stricture. An abscess cavity involving the terminal ileum, distal sigmoid and proximal rectum was identified. Mobilization of the right colon revealed a pocket of purulent material posterior to the proximal ascending colon. En-bloc resection of the terminal ileum, right colon, sigmoid and proximal rectum was performed with two primary anastomoses (ileocolic and colorectal) without stomas.OutcomeIntraoperative pelvic fluid cultures grew Streptococcus viridans and the patient was treated with appropriate antibiotics. Pathology showed perforated appendiceal moderately differentiated adenocarcinoma with abscess formation and direct invasion of the rectum without lymph node involvement (Stage IIC T4bN0Mx, 0/34 lymph nodes). Postoperative course was unremarkable and the patient was discharged home without complications and meeting discharge criteria. The patient was presented at the multidisciplinary tumor board and 6-12 cycles of systemic FOLFOX chemotherapy was recommended because of high-risk features that included T4 depth of invasion, perforation and adherence to the rectosigmoid, concern for micrometastasis, and lymphovascular invasion. However, the patient refused chemotherapy and instead opted for routine surveillance with CEA levels and CT imaging. Postoperative CEA level one month after surgery was 1.7 (from 5.9 and currently 4.3). CT of the chest/abdomen/pelvis 6 months after surgery showed no evidence of recurrence or metastasis. The patient is now 12 months since surgery without evidence of recurrent disease and training for a half marathon.