组织学三联征和聚合酶链反应在弓形虫淋巴结炎病理诊断中的应用

Roles of histologic examination and polymerase chain reaction in diagnosis of toxoplasmic lymphadenitis

目的 经典的组织学三联征诊断法和荧光原位杂交（PCR）法在提高石蜡包埋组织弓形虫淋巴结炎确诊率中的价值.方法 收集本院1999年4月至2009年9月诊断的46例符合组织学三联征形态改变的石蜡包埋淋巴结组织,采用半嵌套式PCR方法 对提取DNA进行弓形虫基因组的片段扩增;另选取30例组织中可见三联征中的二个或一个特征的病例作为对照.结果 组织学三联征组PCR阳性率为76.1%（35/46）,对照组阳性率仅为10.0%（3/30,P〈0.01）;组织学三联征诊断弓形虫淋巴结炎的灵敏度为92.1%（35/38）,特异度为71.1%（27/38）;PCR法的阳性预测值为76.1%（35/46）,阴性预测值为90.0%（27/30）.结论 经典的组织学三联征对于诊断弓形虫淋巴结炎的特异性很强,但敏感性较低,且易漏诊部分非典型病例.在组织形态改变的基础上结合半嵌套式PCR对刚地弓形虫基因片段的检测可大大提高检出敏感性和准确性.

Objective To study the roles of histologic examination and polymerase chain reaction in diagnosis of toxoplasmic lymphadenitis （TL）. Methods Forty-six archival cases of histologically diagnosed TL, encountered during the period from April, 1999 to September, 2009 and with the paraffin-embedded lymph node tissue blocks available, were enrolled into the study. The presence of genome fragments of Toxoplasma gondii （T. Gondii） was analyzed using semi-nested polymerase chain reaction （PCR）. Thirty cases of one or two histopathologic triad of TL as the controls. Results The positive rate of PCR in TL group was 76. 1% （35/46）, as compared to 10.0% （3/30） in the control group. The difference was of statistical significance. The sensitivity and specificity of the histologic triad in diagnosing TL was 92. 1% （35/38） and 71. 1% （27/38） , respectively. The predictive value of positive and negative PCR results was 76.1% （35/46） and 90. 0% （27/30）. Respectively. Conclusions The high specificity but low sensitivity of applying the histologic triad in diagnosing TL cases may be due to the occurrence of atypical histologic pattern. The sensitivity is improved with the use of semi-nested PCR in detecting T. Gondii DNA.