Jejunal Intussusception Secondary to Large Inflammatory Fibroid Polyp

Summary: Inflammatory fibroid polyp (IFP) is a benign mesenchymal lesion that can arise throughout the gastrointestinal tract but are most common in the stomach, followed by the ileum and more rarely in the duodenum and jejunum. Clinical manifestations include intestinal obstruction, abdominal pain, intussusception, and bleeding. Histologically these are characterized by submucosal location, bland spindle stromal cells, abundant eosinophils and lack of lineage specific markers. We report the case of a 68-year-old woman with history of recurrent small bowel obstruction due to Crohn’s disease who presented with jejunal intussusception that required ileocolic resection. Gross examination revealed a 4.2 cm well-circumscribed, lobulated mass with a gray-white and fleshy cut surface. Histologic sections showed a submucosal, nodular proliferation of bland spindle cells embedded within a loose, edematous stroma associated with abundant eosinophils. No hypercellularity, necrosis, hemorrhage, or mitotic figures were identified. Immunohistochemical studies revealed that the lesional cells were positive for vimentin and negative for desmin, SMA, S100, CD1a, CD117, DOG1, ALK, Melan-A, HMB-45, CD34, and STAT6. Ki-67 proliferative index was <1%. The mass was classified as an IFP. IFPs usually express CD34 and negative cases have been described as atypical IFPs. Activating mutations of PDGFRA appear to define this lesion molecularly and are responsible for the recruitment of eosinophils. PDGFRA mutations have been detected in both CD34 positive and negative cases suggesting they represent variants of the same entity. The putative origin of this lesion is hypothesized to be a distinct type of stromal cell: the telocyte. Surgical excision is curative for symptomatic IFP.