It is characterized by a large number of small blood vessels, oedematous connective tissue, and an inflammatory eosinophilic infiltrate.

[14] Inflammatory fibroid polyps emerge from the submucosa and pierce the lamina propria, causing the mucosal layer to bulge.

[15] The inflammatory fibroid polyp is a benign lesion whose cause is unknown;[13] some reports attribute its genesis to myofibroblasts,[16] while others propose vascular or perivascular tissue.

[15] An irritating stimulus is frequently linked to the development of a submucosal granuloma (such as trauma, tuberculosis, helicobacter pylori, Crohn's disease, or sarcoidosis).

[23][24] Isolated reports have been made of inflammatory fibroid polyps at different locations coexisting with granular cell tumors[25] and certain immune system conditions, such as neurofibromatosis,[26] Crohn's disease,[10][27] ankylosing spondylitis,[22] and human immunodeficiency virus infection,[28] however, these results are inconsistent and most likely coincidental.

[29] Activating mutations in the platelet-derived growth factor receptor alpha (PDGFRA) gene were found in 70% of cases in a genetic study involving inflammatory fibroid polyps.

[32] To accurately determine the type of polyp, additional diagnostic techniques such as tandem biopsies, immunohistochemistry staining, and endoscopic ultrasound (EUS) may also be required.

[23] The literature describes four histopathological groups into which inflammatory fibroid polyps can be divided: classical fibrovascular, nodular, sclerotic, and edematous.