Abstract: Objective To investigate the clinicopathological features and differential diagnosis of gastrointestinal stromal tumor （GIST）. Methods 48 cases of GIST were examined by routine HE and immunohistochemical staining and followed up. At the same time， we analyzed the clinicopathological characteristics combined with relevant literature reviews. Results Morphological manifestations of these lesions were diverse. Smooth muscle tumor cells were uniform，mild，braided，and bundled；tumor cells could also have an epithelioid appearance； some tumor cells had a pseudochrysanthemum-shaped mass structure and palisade structure. There was active cell proliferation，including giant multinucleolate and myxoid stroma cells. Vimentin，CD117，Dog-1，and CD34 were all positive in tumor cells. S-100 and SMA were positive in some cases. The Ki-67 increment index increased with tumor grade，which was 2% ～ 25%. p53 was positively expressed in the middle and high levels of lesions. The expression of ER- α36 was strongly positive in tumor cells and localized in the cell membrane/plasma. Follow-up was established in the whole group，10 cases were lost to follow-up，and 11 patients died. Conclusion The GIST is a kind of stromal tumor with different malignant potential. The combined detection of CD117 and Dog-1 can assist the diagnosis and differential diagnosis of GIST. The expression of ER-α36，a new subtype of estrogen receptor-α is highly expressed in GIST，which provides a new research direction for the pathogenesis and treatment of this disease.

Key words: gastrointestinal stromal tumor, immunohistochemistry, differential diagnosis