Isolated Enteric Mastocytosis Causing Recurrent Small Bowel Obstruction

Abstract

Mast cells are involved in many allergenic and non-allergenic inflammatory events in the gastrointestinal (GI) tract. Local proliferation of mast cells can lead to alteration of GI function and systemic symptoms. GI symptoms may include abdominal pain, nausea, vomiting and diarrhea. We report a rare case of isolated mastocytosis of the small bowel causing recurrent small bowel obstruction (SBO). Case Presentation: A 37-year-old male with no significant past medical or surgical history was referred to our center for evaluation of recurrent SBO of unclear etiology. His usual “attacks” presented with abdominal pain and CT scans of abdomen intermittently concerning for a possible small bowel stricture, terminal ileum thickening with upstream dilation of the small bowel. His symptoms would resolve with conservative management. He had no known drug or seasonal allergies. Extensive laboratory and endoscopic evaluations were non-diagnostic and he continued to have 1-2 such episodes per month with no precipitating factors. After 2 years of these “attacks” he was hospitalized again with another episode of SBO. He underwent a proximal ileal segmental resection and primary anastomosis. Pathology revealed significant mast cells infiltration of the small bowel, up to 20/hpf. These results were thought to be suspicious for mastocytic enteritis. His PPI therapy was switched to an H2 blocker to prevent histamine release. The patient has remained symptom free since then for the last 9 months with no further attacks of SBO. Discussion: Mast cells play an important role in the regulation of gastrointestinal visceral sensitivity and vascular permeability. Increased number of mast cells can be seen in the mucosa of patients with inflammatory bowel disease, irritable bowel syndrome, mastocytic enterocolitis, systemic mastocytosis and parasitic infections. Features of mastocytosis in GI biopsies are not well described and difficult to diagnose. In our case, the presentation was very rare with only isolated mastocytosis of the GI tract causing recurrent SBO. Management is aimed at stabilizing mast cells and controlling mediator release with antihistamines and antileukotrienes to prevent symptoms. Conclusion: We present a rare case of recurrent SBO caused by isolated small intestinal mastocytosis without any systemic mastocytosis. This entity should be in the differential diagnosis for potentially rare causes of unexplained, recurrent SBO.