p16 is the most useful diagnostic marker for human papillomavirus (HPV)-associated anogenital lesions. In the cervix, the pattern of p16 immunoreactivity generally correlates with lesion severity. p16 expression in anal intraepithelial neoplasia (AIN) is far less studied. Whether such correlation holds true has to be determined. We correlated the degree and pattern of p16 immunohistochemistry (IHC) results with morphologic diagnoses of 1000 anal squamous and transitional zone biopsy specimens. Using the Lower Anogenital Squamous Terminology criteria, p16 IHC results were classified as block staining, partial staining, or negative. Among 150 samples without morphologic evidence of AIN, p16 was negative in 85% and partial staining in 15%. AIN 1 (n=400) revealed diverse results: 28% negative, 35% partial, and 37% block staining. Among AIN 2 (n=298), 89% were block, 9% partial staining, and 2% negative. AIN 3 (n=152) revealed block (95%) or partial staining (5%). For the detection of AIN 2/3, p16 block staining yielded 91% sensitivity, 73% specificity, 80% positive predictive value, 91% negative predictive value, and a Youden Index of 0.64. Combining block staining and partial staining slightly increased sensitivity (99%) and negative predictive value (98%), but significantly decreased specificity (43%), positive predictive value (59%) and Youden Index (0.42, P<0.001). As with the cervix, p16 immunoreactivity correlates with morphologic diagnoses of AIN. Block staining offers the optimal diagnostic value for AIN 2/3. Caution is required since AIN 1 frequently exhibits block staining; the prognostic value of p16 warrants further investigation.

中文翻译：

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p16 免疫反应性与 HPV 相关肛门上皮内瘤变的形态学诊断相关：1000 个活检组织的研究。

p16 是人乳头瘤病毒 (HPV) 相关肛门生殖器病变最有用的诊断标记物。在子宫颈中，p16 免疫反应性模式通常与病变严重程度相关。p16 在肛门上皮内瘤变 (AIN) 中的表达研究较少。必须确定这种相关性是否成立。我们将 p16 免疫组织化学 (IHC) 结果的程度和模式与 1000 份肛门鳞状和移行区活检标本的形态学诊断相关联。使用下肛门生殖器鳞状细胞术语标准，p16 IHC 结果分为块染色、部分染色或阴性。在 150 个没有 AIN 形态学证据的样本中，85% 的 p16 呈阴性，15% 的部分染色。AIN 1 (n=400) 显示不同的结果：28% 阴性、35% 部分染色和 37% 块染色。在 AIN 2 (n=298) 中，89% 为封闭，9% 为部分染色，2% 为阴性。AIN 3 (n=152) 显示块状染色 (95%) 或部分染色 (5%)。对于 AIN 2/3 的检测，p16 块染色产生 91% 的敏感性、73% 的特异性、80% 的阳性预测值、91% 的阴性预测值和 0.64 的 Youden 指数。结合块染色和部分染色略微提高了敏感性（99%）和阴性预测值（98%），但显着降低了特异性（43%）、阳性预测值（59%）和约登指数（0.42，P<0.001）。与子宫颈一样，p16 免疫反应性与 AIN 的形态学诊断相关。块染色为 AIN 2/3 提供最佳诊断价值。需要小心，因为 AIN 1 经常出现块染色；p16 的预后价值值得进一步研究。