关键词: 口腔黏膜, 髓外髓细胞肉瘤, 临床病理

Abstract: Objective To approach the clinical and pathologic features，diagnosis and differential diagnosis of extramedullary myeloid sarcoma in order to know more about it. Methods The clinical manifestations，histomorphology featrures，immunohistochemistry，treatment and prognosis were analyzed in three cases of extramedullary myeloid sarcoma of the mouth mucosa with review of the literatures. Results Three cases of extramedullary myeloid sarcoma of the mouth mucosa all presented gingival enlargement. Morphologically，the tumor cells grew in a diffuse pattern and were small to medium in size，with scant cytoplasm，round or oval nuclear，exquisite chromatin，and frequent karyokinesis. Immunohistochemistry for MPO were all positive in three cases，and CD43 and CD117 were positive in two cases. Conclusions Extramedullary myeloid sarcoma is rare.Only with morphology，it may be misdiagnosed as lymphoma，small cell carcinoma and so on.Immunohistochemistry can contribute to diagnosis and differential diagnosis so as to guide the doctors to give patients appropriate treatment.

Key words: mouth mucosa, extramedullary myeloid sarcoma, clinicopathology