Inflammatory Fibroid Polyps of Large Bowel with PDGFRA Mutation

The presence of the platelet-derived growth factor receptor α (PDGFRA) gene mutation was examined in 2 cases of inflammatory fibroid polyp (IFP) in the large bowel. Immunohistochemical analysis of PDGFRA revealed one positive (Case 1) and one negative (Case 2) IFP. The lesions were then selectively microdissected from paraffinembedded specimens, based on typical histological features showing bland spindled cells arranged in whorls or in onionskin-like fashion around blood vessels or mucosal glands with eosinophilic cells. Case 1 carried a deletion with additional missense mutation causing framshifted-nonsense mutation in exon 14; Case 2 carried a missense mutation in exon 18. These findings confirmed that IFPs in the large bowel, albeit very rare, also share genetic alterations of PDGFRA similar to those in other gastrointestinal IFPs.