【摘要】 髓外浆细胞瘤（EMP）在犬中属于相对罕见的肿瘤，为了明确犬EMP的组织病理学和免疫标志物表达特征，本试验采用苏木精-伊红（H. E.）染色和刚果红染色法对患犬的皮肤肿物进行组织病理学诊断，进一步使用EMP免疫标志物配对盒基因5(PAX5)、白细胞分化抗原20(CD20)、白细胞分化抗原79a(CD79a)、多发性骨髓瘤基因1(MUM1)和犬免疫球蛋白G(Canine IgG)进行免疫组织化学（IHC）染色，并总结免疫标志物表达特征。结果显示，2例病例的肿物均无包膜结构，并与周围组织边界清晰，肿瘤细胞呈浆细胞样或浆母细胞样特征，病例2肿物内见淀粉样沉积。病例1肿瘤细胞免疫标志物PAX5、CD20和MUM1呈阴性，CD79a和Canine IgG呈阳性；病例2肿瘤细胞免疫标志物PAX5呈阴性，CD20、CD79a、MUM1和Canine IgG呈阳性。结果表明，通过组织病理学检查结合IHC染色结果，确诊2例病例均为犬皮肤型EMP。本试验为犬EMP的精确诊断提供重要的病理学依据，具有重要的参考价值。更多还原

【Abstract】 Extramedullary plasmacytoma(EMP) is a relatively rare tumor in dogs. To investigate the histopathological and immunohistochemical characteristics of canine EMP, this study analyzed skin tumor samples from affected dogs using hematoxylineosin(H. E.) staining and Congo red staining for histopathological diagnosis. Immunohistochemical(IHC) staining was further performed to examine the expression of EMP-specific markers, including paired box gene 5(PAX5), cluster of differentiation 20(CD20), cluster of differentiation 79a(CD79a), multiple myeloma oncogene 1(MUM1), and canine immunoglobulin G(Canine IgG). The results showed that the tumors in both cases lacked encapsulation but were well-demarcated from surrounding tissues.Tumor cells exhibited plasmacytoid or plasmablastic characteristics, and amyloid deposition was observed in the tumor tissue of Case 2. Immunohistochemically, the tumor cells in Case 1 were negative for PAX5, CD20, and MUM1, but positive for CD79a and Canine IgG. In Case 2, the tumor cells were negative for PAX5, but positive for CD20, CD79a, MUM1, and Canine IgG. These findings confirmed that both cases were cutaneous forms of canine EMP based on histopathological and IHC results. This study provides significant pathological evidence for the accurate diagnosis of canine EMP, serving as an important reference for clinical and research purposes.更多还原