Inflammatory Fibroid Polyp With Central Pseudocystic Degeneration

Inflammatory fibroid polyps (IFP) are uncommon benign lesions of the gastrointestinal tract that can mimic malignant neoplasms, cause intussusception, and be difficult to recognize radiologically. Previous descriptions in the medical literature have consistently noted them to be composed of a solid core of fibrous tissue with overlying mucosa. A 47-year-old woman presented with 1 month of abdominal pain. Computed tomography (CT) with intravenous contrast revealed persistent obstruction due to enteroenteric intussusception. An ill-defined ovoid structure isodense with small bowel was noted to be contiguous with a collapsed loop of adjacent intestine. Surgical exploration identified an 8 cm polyploid intraluminal mass of the proximal ileum, which was resected. Histological findings were characteristic of an IFP. However, the polyp's mesenchymal center exhibited pseudocystic degeneration, resulting in a space filled with serosanguineous fluid. Cystic spaces can be found in other mesenchymal lesions, but mimics of IFP were excluded in this patient by negative immunohistochemistry (IHC) studies with S100, KIT, DOG1 (ANO1), and ALK. To our knowledge, central pseudocystic degeneration represents an underrepresented presentation of IFP, and the current lesion exhibited a radiologically deceptive appearance which could mimic other, potentially malignant entities.