INFLAMMATORY FIBROID POLYP
LAST UPDATE: 09/11/2024
GENERAL
Benign mesenchymal neoplastic polyp from submucosa
found in stomach and small intestine
Associated with PDGFRA mutation
formerly eosinophilic granuloma
SITES
Mainly in pylorus or distal antrum
ETIOLOGY
Can be familial (e.g., Devon polyposis syndrome)
CLINICAL PRESENTATION
Common in 6th-7th decades.
Solitary, small, sessile
Median size: 1.5 cm, can reach up to 9 cm
Rare association with adenocarcinoma
MICROSCOPY
Submucosal lesion with spindle and stellate cells
Expands submucosa with fibromyxoid stroma
Can infiltrate lamina propria
Loose, edematous, fibromyxoid stroma
Rich in eosinophils and mixed inflammatory infiltrate
Onion-skin arrangement of spindle cells around vessels
Minimal mitotic activity
IHC
USUALY Positive: CD34, vimentin
USUALY NEGATIVE: C-KIT, S100, DOG1
EVENTUALY POSITIVE: SMOOTH MUSCLE ACTIN, FASCIN
MOLECULAR
PDGFRA mutation
Differential diagnosiS
Gastrointestinal stromal tumor (CD117+)
Plexiform fibromyxoma (lacks concentric vessels)
Schwannoma (S100+, peripheral lymphoid cuffing)
images
REFERENCES
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