Previously known as: eosinophilic granuloma, inflammatory pseudotumor
Location: usually in the gastric antrum
Appearance: sessile or pedunculated polyp arising in the submucosa
Clinical features:
(1) often asymptomatic
(2) can cause gastric outlet obstruction
(3) can cause colicky abdominal pain
Histologic features:
(1) spindle cell proliferation, composed of fibroblasts or myofibroblasts
(2) often vascular
(3) chronic inflammation with prominent eosinophils
Immunohistochemical stains that are frequently positive:
(1) vimentin
(2) CD34
(3) CD64
(4) bcl-2
Immunoperoxidase stains that are negative:
(1) CD117 (for gastrointestinal stromal tumor)
(2) S100 (for neurofibroma)
