Abstract

Background: Small bowel adenocarcinomas (SBA) are rare, comprising about 1-3% of all malignant GI tumors. Evidence suggests that patients with Crohn's disease (CD) are at increased risk of SBA compared to the general population; however, the diagnosis can be challenging as symptoms and imaging findings can mimic inflammatory bowel disease (IBD). Methods: We present a case of SBA in a patient with CD to highlight the difficulties in diagnosis of this rare entity that was further delayed by barriers to healthcare access. Case Report A 38-year-old man with CD presented to clinic with severe right-sided abdominal pain, nausea/vomiting, and weight loss (BMI 15). Exam showed a palpable, tender right-lower-quadrant mass. Labs revealed leukocytosis (WBC 14.2 cells/mm3), anemia (Hgb 9.0 g/dL), thrombocytosis (platelets 651 cells/mm3), elevated inflammatory markers (ESR 116 mm/h; CRP 239 mg/L), and hypoalbuminemia (1.7 g/dL). He was subsequently admitted to the hospital. The patient was originally diagnosed with CD 5 years prior while incarcerated, based on mild colonic inflammation on colonoscopy. Capsule endoscopy was recommended but never performed. CT enterography showed multifocal strictures as well as a distal ileal inflammatory stricture with intramural collection queried to represent early penetrating disease. Adalimumab was initiated with clinical response, although occasional gaps in therapy arose due to barriers accessing care. In the past year, weight loss and hypoalbuminemia raised concern for an alternate etiology. Colonoscopy was recommended, but the patient was lost to follow-up. At the time of his current presentation, MRI enterography showed long-segment distal ileal inflammation with a 6-cm abscess and hepatic lesions thought to be benign hemangiomas. Colonoscopy showed a non-traversable stricture at the ileocecal valve. The abscess was percutaneously drained, and TPN was initiated. He underwent planned ileocolonic resection 1 month later, which showed extensive inflammation requiring resection of 60 cm of small bowel. Liver lesions were also noted intra-operatively, initially suspected to be abscesses. Surgical pathology of the terminal ileum stricture showed poorly differentiated invasive adenocarcinoma with sarcomatoid components. Results: Biopsy of the liver lesions confirmed metastatic SBA, and the patient was referred to oncology. Conclusions: SBA is a rare but aggressive malignancy that can present with non-specific symptoms. Early detection leads to improved outcomes, but diagnosis is challenging in patients with underlying pathology such as CD as highlighted by this case. Moreover, patients with CD have an 8-fold increased risk of SBA likely due to chronic inflammation with the vast majority arising from an affected bowel segment. On imaging, these cancers can appear indistinguishable from CD-related fibrosis and inflammation. Thus, SBA are often found incidentally during surgery at more advanced stages. Compared to imaging, capsule endoscopy and/or small bowel enteroscopy may increase diagnostic yield in patients with a higher index of suspicion for SBA. In addition to underlying penetrating CD complicating diagnosis, social determinants of health further impacted this patient's clinical course. His difficulties accessing care resulted in lapses in treatment and delay in outpatient endoscopy. Overall, the absolute risk of SBA in CD is quite low and thus, routine surveillance would not be cost-effective. However, further work is needed to improve early detection.