Pen Foreign Body Ingestion Mimicking Crohn’s Disease in a Pediatric Patient

Introduction: Foreign body ingestion is a common problem in pediatrics, particularly in children with psychiatric illness. Foreign bodies present for extended periods of time can trigger a local inflammatory reaction causing weight loss, abdominal pain, and elevated inflammatory markers, mimicking inflammatory bowel disease (IBD). We report a rare case of intentional pen ingestion in a 13-year-old, whose clinical presentation was initially suspicious for Crohn’s disease due to foreign body reaction.

Case Description: A 13-year-old male with PMH of constipation, ADHD, and depression presented to the ED with 3 days of RLQ abdominal pain, 3 months of intermittent generalized abdominal pain, and a 10-pound weight loss over six months. Vital signs were stable. Exam revealed right-sided abdominal tenderness without rebound. He endorsed dysuria, nausea, and constipation, but denied fevers, rash, ulcers, and arthralgias. Family history included ulcerative colitis in an uncle.

Laboratory workup showed elevated inflammatory markers (CRP 306, ESR 58), leukocytosis (WBC 29), and normal fecal calprotectin. Abdominal ultrasound showed inflammatory changes most pronounced at the terminal ileum. MRE demonstrated RLQ inflammation around the thick-walled terminal ileum, thought to be concerning for IBD.

This patient was admitted, started on Metronidazole, and scheduled for endoscopy and colonoscopy. Endoscopy showed normal esophagus with scattered aphthae and erythema in the stomach. On colonoscopy, the team was surprised to find a 14.1 cm pen impacted in the left colon (Image 1). The foreign body was removed via snare.

Following the colonoscopy, the patient disclosed swallowing the pen five months prior to presentation in a suicide attempt. He received 48 hours of IV Piperacillin-Tazobactam for microperforation coverage and was transferred to a voluntary psychiatric admission. Two days following the procedure, his CRP had decreased to 53 and his WBC to 7.8. Ten days following, his CRP had normalized, and his abdominal pain had resolved. He continued psychiatric care and has remained asymptomatic since discharge.

Discussion: Foreign body reactions mimicking IBD have been reported but are very rare, particularly in pediatric patients. Objects >6 cm rarely traverse the duodenum C-loop. 10-20% of objects fail to pass through the gastrointestinal tract and can cause small bowel inflammation, obstruction, perforation, and fistula formation. Foreign body reaction at the site of impaction causes a local inflammatory response with bowel wall thickening. Much of this pathology also commonly occurs in IBD.

Conclusion: Foreign body reaction can mimic IBD, and a careful history of potential foreign body ingestions should be taken in all pediatric patients presenting with abdominal pain and weight loss, particularly in the setting of studies concerning for small bowel inflammation and in patients with psychiatric illness. Laboratory and imaging studies alone are not sufficient in differentiating between IBD and foreign body reaction, and colonoscopy remains a necessary diagnostic tool.