Gastroenterology clinical image challenge: A 5-year-old, previously healthy boy was transferred from an outside facility with concern for appendicitis. He had been complaining of intermittent, periumbilical abdominal pain for the past two weeks with episodes occurring every four to five days and lasting one hour before self-resolving. Just before presentation, his pain worsened to the point that he was no longer able to sit up or walk. The pain was associated with decreased appetite; however, the family denied fever, weight loss, diarrhea, blood in stool, oral ulcers, nausea or vomiting. When asked, they reported recent episodes of bilateral shin pain at night and an eczematous rash. Several other children in their community had a one-day “stomach bug” one to two weeks prior.
The family history was negative for inflammatory bowel disease. Both surgery and GI were consulted and recommended a right lower quadrant (RLQ) abdominal ultrasound (US) examination plus C-reactive protein and erythrocyte sedimentation rate. Pertinent examination findings included weight at the 61st percentile for age, an ill-appearing but nontoxic male, hyperactive bowel sounds in the right hemiabdomen (difficult to auscultate or absent in the left hemiabdomen), a soft though diffusely tender abdomen to palpation worse in the periumbilical and RLQ regions with voluntary guarding.
Per report, the initial laboratory evaluation at an outside facility including a complete blood count with differential, comprehensive metabolic panel, amylase and lipase was completely normal. The outside facility’s computed tomography (CT) scan of the abdomen and pelvis with contrast (Figure) demonstrated “severe wall thickening with luminal narrowing involving the distal 5–6 cm of the terminal ileum.” The RLQ abdominal US examination demonstrated a “linear, 3 cm, highly echogenic foreign body within the lumen of the terminal ileum, with each end protruding through the bowel wall.”
What is the diagnosis?