Abstract: A Clinicopathologic Analysis of 65 Cases of Histiocytic Necrotizing LymphadenitisWhich Canbe Easily Misdiagnosed as LyphomaYinghong YANG1, Yuhui ZHENG1, Jianping HUANG1, Tao YANG2, Hua CHEN2Correspondence to: Yinghong YANG, E-mail: yyh1555@163.com1Department of Pathology, Union Hospital of Fujian Medical University, Fuzhou 350001, China2Public Health School, Fujian Medical University, Fuzhou 350001, ChinaAbstract Objective: To study the clinicopathologic features of 65 histiocytic necrotizing lymphadenitis ( HNL ) cases and to ex-plore the differentiatial diagnosis between HNL and lyphoma. Methods: A total of 65 HNL cases with routine section of lymph node bi-opsies, immunophenotypes detected by immunohistochemistry s-p methods and results of EBER in situ hybridization were retrospec-tively analyzed. Results: There were 31 males ( 47.7% ) and 34 females ( 52.3% ) and the ratio of male to female was 1:1.1. Eighteencases ( 27.7% ) were younger than 20 years, 26 cases (40.0%) were between 20 and 30 years, and 13 cases ( 20.0% ) were older than 30years. Twenty cases ( 30.8% ) had fever. The size of lymph node of 48 cases ( 73.9% ) was 1.5cm to 3.0cm. Microscopy showed thatthe structure of lymph nodes was intact in 56 cases ( 86.2% ), partially destroyed in 7 cases (10.8%), and completely destroyed in 2 cas-es ( 3.1% ). One case had a large necrosis lesion ( 1.53% ). Sixty-two cases ( 95.4% ) had multiple necrosis lesions and 33 cases(50.08% ) showed fusion necrosis lesions. The 3 phases of pathologic characteristics ( proliferative, necrotizing and xanthomatous )were observed simultaneously in the same lymph node. Immunohistochemistry showed a large number of CD68 positive cells in thelymph nodes. EBER showed 14 positive cases ( 21.5% ) and 51 negative cases ( 78.5% ). Stepwise logistic analysis showed no relation-ship of sex, fever, and EBER with other parameters ( P > 0.05 ). Multiple linear regression analysis showed a correlation between thestructure of lymph node and the percentage of cells in necrosis phase ( Y = 0.012 + 0.008X, Y indicates the structure of lymph node, Xindicates the percentage of cells in necrosis phase ). No relationship was found between multiple necrosis lesions of the cortex and otherparameters ( P > 0.05 ). No relationship was found between the fusion necrosis lesions of the cortex and other parameters ( P > 0.05 ).The percentages of cells in proliferative phase and necrosis phase were correlated with fusion necrosis of cortex and perinesions of transformative lymphocytes. The percentage of cells in xanthomatosis phase was correlated with necrosis of cortex and pa-tients' age. Conclusion: The three histopathologic characteristics of HNL were criteria for its diagnosis. HNL should be differentiatedfrom TB and lymphoma.Keywords Histiocytic necrotizing lymphadenitis; Immunohistochemistry; EBER in situ hybridizationcrosis le-sions of transformative lymphocytes. The percentage of cells in xanthomatosis phase was correlated with necrosis of cortex and pa-tients' age. Conclusion: The three histopathologic characteristics of HNL were criteria for its diagnosis. HNL should be differentiatedfrom TB and lymphoma.Keywords Histiocytic necrotizing lymphadenitis; Immunohistochemistry; EBER in situ hybridization