Click
on thumbnails to see full sized pictures.Gastrointestinal Pathology- Clinicopathologic Correlation in Mucosal Biopsy
Case #6 (question #9):
A 67 year-old woman with heme-positive stool. Endoscopy revealed a gastric polyp. Representative images are illustrated below:
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Question No. 9. The Answer is: (C) It is thought to be reactive in nature.
Discussion: The polyp is morphologically and immunophenotypically consistent with an inflammatory fibroid polyp (IFP). Histologically IFP is characterized by mesenchymal proliferations composed of a mixture of cytologically bland stromal spindle cells, small blood vessels, and inflammatory cells. Eosinophils are often prominent whereas mitotic figures are rare. The lesion is thought to be a reactive overgrowth of fibrovascular connective tissue. Immunohistochemically, the stromal cells are typically positive for vimentin and CD34 and a smaller proportion are positive for SMA and HHF-35. They are uniformly negative for c-kit (CD117) and do not respond to Gleevac. The positive cells in the immunohistochemistry for c-kit are mast cells. The median size is 1.5 cm. It may occur anywhere in the gastrointestinal tract. The most common sites are in the stomach and small intestine. IFP may be found incidentally but large lesions can cause obstructive symptoms. Although eosinophilic gastroenteritis sometimes enters the differential diagnosis, there is no peripheral eosinophilia.