Inflammatory fibroid polyp of the ileum with stroma rich in lymphovascular structures

Abstract

Inflammatory fibroid polyp (IFP) is a rare and benign tumor of the gastrointestinal (GI) tract that harbors PDGFRA mutations. PDGFRA alterations are also found in subsets of other GI tract mesenchymal tumors, such as KIT-negative gastrointestinal stromal tumors and inflammatory myofibroblastic tumors. We report a case of ileal IFP with uncommon histological features. A 71-year-old woman was referred to our hospital with abdominal pain. She was diagnosed with intestinal intussusception. Laparoscopic surgery was performed and the ileum was resected by 50 cm. Microscopically, tumor cells with round nuclei and prominent nucleoli proliferating within the collagenous fibrous stroma were observed. Some spindle-shaped cells and lymphoplasmacytic infiltrations were also observed, and eosinophils were scattered throughout the lesion. Lymphovascular structures of various sizes were prominent in the stroma. Immunohistochemistry revealed PDGFRA overexpression but did not show positive staining for CD34. The tumor had a heterozygous deletion of five amino acids in exon 12 (del 1696-1710, Δ566-570) of PDGFRA. Based on these findings, a diagnosis of IFP was made. The patient remains alive without any evidence of recurrence.

Keywords

• Inflammatory fibroid polyp
• Inflammatory myofibroblastic tumor
• Gastrointestinal stromal tumor
• PDGFRA
• Mutation
• Immunohistochemistry