Inflammatory fibroid polyp (Vanek tumor) is a rare, benign submucosal lesion of the gastrointestinal tract, of mesenchymal origin, containing fibrovascular stromal proliferation in the submucosa with prominent eosinophilic infiltration. It is most commonly found in the gastric antrum (70-75%), followed by small bowel and colon. It is typically detected at ages 50-60 with slight female predominance. On CT, it appears as a well-defined, homogeneously or mildly heterogeneously enhancing submucosal mass. Large lesions may show intraluminal polypoid extension and may cause intussusception in the small bowel. Histologically, the triad of spindle stromal cells, prominent capillary network, and dense eosinophilic infiltration is characteristic. PDGFRA mutation is detected in a proportion of cases. Surgical or endoscopic excision is curative and recurrence is extremely rare.
Age Range
40-80
Peak Age
65
Gender
Equal
Prevalence
Rare
Inflammatory fibroid polyp originates from mesenchymal cells in the submucosa, and whether it represents a reactive or neoplastic process is debated. Recent studies show PDGFRA (platelet-derived growth factor receptor alpha) gene mutations detected in 55-60% of cases — supporting classification of IFP as low-grade neoplasm rather than reactive process. PDGFRA activation stimulates stromal cell proliferation and chemotactic cytokine secretion, causing prominent eosinophilic infiltration. Histologically, the lesion contains fibrovascular stroma composed of spindle stromal cells (CD34 positive, CD117 negative) in the submucosa, dense eosinophils infiltrating this stroma, and prominent capillary proliferation ('onion-skin' perivascular pattern). The rich capillary network forms the physical basis for moderate enhancement on CT — contrast material accumulates in neovascular capillaries. Eosinophilic infiltration may cause edema and inflammatory changes around the lesion — reflected as perilesional density increase on CT. Despite shared PDGFRA mutation with GIST, CD117 (c-kit) negativity and benign biological behavior clearly differentiate IFP.
Histologically, concentric arrangement of spindle stromal cells around capillary vessels — forming perivascular 'onion-skin' pattern. This pattern is highly characteristic of IFP and used for differentiation from other submucosal mesenchymal tumors. Not directly assessable on imaging but cornerstone of histopathological diagnosis.
In CT arterial phase, a well-defined, homogeneous or mildly heterogeneous, moderately enhancing submucosal mass is observed in the gastric antrum. Enhancement is not as prominent as GIST and not as hypervascular as glomus tumor. The lesion is usually oval or polypoid shaped and may show intraluminal growth.
Report Sentence
A [size] mm well-defined, homogeneously moderately enhancing submucosal mass in the gastric antrum is identified, potentially consistent with inflammatory fibroid polyp.
In portal venous phase, the lesion maintains enhancement without significant washout. Enhancement intensity may slightly increase or remain stable compared to arterial phase — delayed enhancement pattern reflects fibrovascular stroma and collagen deposition.
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In portal venous phase, the lesion demonstrates persistent enhancement without washout.
On T2-weighted sequences, the lesion shows intermediate to hyperintense signal. T2 signal intensity varies depending on water content between stromal collagen and eosinophilic infiltrate. Homogeneous signal pattern reflects uniform histological composition.
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On MRI T2-weighted sequence, the lesion demonstrates intermediate to hyperintense signal with homogeneous signal pattern.
On EUS, a well-defined, hypoechoic or mildly heterogeneous mass originating from submucosa or muscularis mucosa is observed in the gastric antrum. May show polypoid growth pattern — with a stalk or broad base extending into the lumen. Color Doppler shows moderate vascularity.
Report Sentence
On EUS, a [size] mm well-defined, hypoechoic polypoid mass originating from the submucosa is identified in the gastric antrum.
On diffusion-weighted imaging (DWI), the lesion does not show significant diffusion restriction — ADC values are normal or mildly decreased. This finding supports the benign nature and helps differentiate from highly cellular malignant tumors.
Report Sentence
On DWI, the lesion shows no significant diffusion restriction without signal loss on ADC map.
On non-contrast CT, a homogeneous, well-defined intramural or polypoid mass of soft tissue density (30-45 HU) is observed. No calcification, necrosis, or hemorrhage. No surrounding fat infiltration — reflecting benign nature.
Report Sentence
On non-contrast CT, a [size] mm homogeneous, well-defined mass of soft tissue density in the gastric antrum is identified without calcification or necrosis.
Criteria
Most common type located in gastric antrum. Usually shows polypoid growth, submucosal or intraluminal extension.
Distinct Features
1-5 cm diameter, rarely larger. Can be treated with endoscopic polypectomy. Low intussusception risk.
Criteria
Type located in small bowel (especially ileum). Frequently causes intussusception and presents with acute abdomen.
Distinct Features
Target sign on CT — intussusception finding. Surgical resection usually required. Preoperative diagnosis is difficult.
Criteria
Subtype with positive PDGFRA gene mutation (55-60%). Considered a low-grade neoplasm.
Distinct Features
Clinically and radiologically indistinguishable from other types. Diagnosis requires genetic analysis. Despite shared mutation with GIST, CD117 negative and shows benign behavior.
Distinguishing Feature
GIST usually larger, heterogeneous enhancement, may show necrosis/cavitation, CD117 positive; IFP smaller, homogeneous, CD117 negative, CD34 positive
Distinguishing Feature
Hyperplastic polyp mucosal origin, no submucosal component; IFP submucosal origin, shows deeper layer involvement on EUS
Distinguishing Feature
Carcinoid tumor more prominent arterial enhancement, chromogranin A positive; IFP moderate enhancement, eosinophilic infiltration prominent on histology
Distinguishing Feature
Heterotopic pancreas shows central umbilication and pancreas-like enhancement; IFP has no central umbilication and different enhancement pattern
Urgency
routineManagement
surgicalBiopsy
NeededFollow-up
no-follow-upInflammatory fibroid polyp is an entirely benign lesion with no malignant transformation potential. Endoscopic polypectomy (small, pedunculated lesions) or surgical excision (large or complicated lesions) is curative. Recurrence is extremely rare. Intestinal IFP with intussusception may require emergency surgery. Endoscopic resection is usually sufficient for gastric IFP. PDGFRA mutation presence does not change treatment approach, but immunohistochemistry is essential for GIST exclusion in the diagnostic process (CD117 negativity must be confirmed).
Inflammatory fibroid polyp is entirely benign. Curatively treated with endoscopic or surgical polypectomy. Malignant transformation has not been reported. Large lesions may cause obstruction or intussusception.