Reflectance confocal microscopy (RCM) with endogenous backscattered contrast can noninvasively image basal cell carcinomas (BCCs) in skin. However, BCCs present with high nuclear density, and the relatively weak backscattering from nuclei imposes a fundamental limit on contrast, detectability, and diagnostic accuracy. We investigated PARPi-FL, an exogenous nuclear poly(adenosine diphosphate ribose) polymerase (PARP1)–targeted fluorescent contrast agent, and fluorescence confocal microscopy toward improving BCC diagnosis. Methods: We tested PARP1 expression in 95 BCC tissues using immunohistochemistry, followed by PARPi-FL staining in 32 fresh surgical BCC specimens. The diagnostic accuracy of PARPi-FL contrast was evaluated in 83 surgical specimens. The optimal parameters for permeability of PARPi-FL through intact skin was tested ex vivo on 5 human skin specimens and in vivo in 3 adult Yorkshire pigs. Results: We found significantly higher PARP1 expression and PARPi-FL binding in BCCs than in normal skin structures. Blinded reading of RCM–and–fluorescence confocal microscopy images by 2 experts demonstrated a higher diagnostic accuracy for BCCs with combined fluorescence and reflectance contrast than for RCM alone. Optimal parameters (time and concentration) for PARPi-FL transepidermal permeation through intact skin were successfully determined. Conclusion: Combined fluorescence and reflectance contrast may improve noninvasive BCC diagnosis with confocal microscopy.

具有内源性反向散射对比的反射共聚焦显微镜 (RCM) 可以对皮肤中的基底细胞癌 (BCC) 进行非侵入性成像。然而，BCC 具有高核密度，并且来自核的相对较弱的反向散射对对比度、可检测性和诊断准确性施加了根本限制。我们研究了 PARPi-FL，一种外源性核聚（腺苷二磷酸核糖）聚合酶 (PARP1)-靶向荧光造影剂，以及荧光共聚焦显微镜以改善 BCC 诊断。方法：我们使用免疫组织化学检测了 95 个 BCC 组织中的 PARP1 表达，然后对 32 个新鲜手术 BCC 标本进行了 PARPi-FL 染色。在 83 个手术标本中评估了 PARPi-FL 对比的诊断准确性。PARPi-FL 通过完整皮肤渗透性的最佳参数在 5 个人皮肤样本上进行了离体测试，在 3 只成年约克夏猪身上进行了体内测试。结果：我们发现 BCC 中的 PARP1 表达和 PARPi-FL 结合明显高于正常皮肤结构。2 位专家对 RCM 和荧光共聚焦显微镜图像的盲读表明，与单独使用 RCM 相比，联合荧光和反射对比对 BCC 的诊断准确性更高。成功确定了 PARPi-FL 通过完整皮肤经表皮渗透的最佳参数（时间和浓度）。结论：结合荧光和反射对比可以改善共聚焦显微镜的无创 BCC 诊断。