INFLAMMATORY FIBROID POLYP

Clinical Features

Inflammatory fibroid polyps are mesenchymal proliferations composed of a mixture of stromal spindle cells, small blood vessels, and inflammatory cells, particularly eosinophils.[190–192] They may occur anywhere in the GI tract but are most common in the stomach and small intestine. In the stomach, inflammatory fibroid polyps usually occur in the sixth decade of life. Recent studies have reported a disproportionately large number of gastric inflammatory fibroid polyps in female patients.[193], [194] Some have suggested an infectious etiology for inflammatory fibroid polyps.[191], [192] However, no causative agent has ever been identified[195]; thus, most observers currently consider inflammatory fibroid polyps to be a form of reactive pseudotumor. When small, these tumors may be discovered incidentally at endoscopy. However, large lesions may cause obstructive symptoms such as nausea, vomiting, and abdominal pain. In some cases, inflammatory fibroid polyps may contain a long stalk; these may prolapse through the pyloric sphincter and cause obstruction.[196] Some studies suggest that inflammatory fibroid polyps are more common among patients with atrophic gastritis and pernicious anemia.

Pathologic Features

Inflammatory fibroid polyps are typically small, wellcircumscribed, submucosally based, sessile lesions that may show ulceration of the overlying mucosa. Their median size is 1.5cm, and, although most lesions are smaller than 3cm in diameter, polyps that measure as large as 5cm in diameter have been reported. In the stomach, they most commonly arise in the antrum, immediately proximal to, or overlying, the pyloric sphincter.

Microscopically, inflammatory fibroid polyps are submucosal tumors and often show an abrupt demarcation at the level of the muscularis propria. Mucosal involvement is common with gastric lesions. However, unlike small intestinal lesions, involvement of the muscularis propria is unusual in gastric polyps. Extension of the tumor into the mucosa causes separation of gastric glands, which results in a disordered and atrophic appearance. Inflammatory fibroid polyps are composed of a loose mixture of spindle-shaped, plump, cytologically bland stromal cells, inflammatory cells, and small, thin-walled blood vessels in an edematous or myxoid background (Fig. 17-21). In the stomach, stromal cells often proliferate in a concentric fashion around small and medium-sized blood vessels.[197], [198] Mitotic figures are rare but may occasionally be present in deeper portions of the lesion. Atypical mitoses are never present. Eosinophils are a prominent inflammatory component and may also encircle vessels. Larger lesions may show collagen deposition and smooth muscle proliferation, or even giant cell formation.

Immunohistochemically, stromal cells have been reported to be positive for vimentin, CD34, fascin, CD35, cyclin D1, and calponin.[194,197–201] A smaller proportion are also positive for smooth muscle actin, HHF-35, KP-1, and Mac-387.[194,197–201] In contrast to stromal tumors of the GI tract, stromal cells in inflammatory fibroid polyps are negative for CD117 (c-kit).[194], [197] Although the histogenesis of inflammatory fibroid polyps remains controversial, a possible origin in dendritic cells or CD34-positive perivascular cells has been proposed.[194], [201] Differentiating between inflammatory fibroid polyps and inflammatory myofibroblastic tumors is discussed next.

认真学习了一下，谢谢老师

GIST

（胃）病变倾向于GIST1期。

 网上找到一个病例，大家见链接吧！

http://bbs.ipathology.cn/article/401747.html

GIST

加做dog-1,若阴性，则考虑

炎性纤维性息肉

gist

胃粘膜下的肿块，2cm，还是往最常见的地方考虑，间质瘤，神经鞘瘤，肌纤维母细胞瘤等，CD34阳性还是要考虑间质瘤的！1）、免疫组化Dog-1和Nestin检测；2）、血小板衍生因子的基因突变检测进一步确诊间质瘤。

学习啦！

 CD34阳性，考虑GIST，加做dog-1   特异性比较强。

已加做： dog-1、nestin阴性表达。