The distinction between mucinous carcinomas (MCs) and mucocele-like lesions (MLLs), particularly those containing detached epithelial fragments, can be problematic in the limited samples afforded by breast core needle biopsies (CNBs). Neovascularization of mucin has been proposed as a criterion to distinguish MC from MLL, but its value in helping to categorize mucin-producing breast lesions in CNB has not been previously investigated. To address this, we evaluated mucin neovascularization on hematoxylin and eosin (H&E)-stained sections of 140 CNB containing mucin-producing breast lesions including 52 MC, 17 mucin-producing ductal carcinoma in situ (mDCIS), and 71 MLL. In 116 cases with sufficient remaining material (42 MC, 16 mDCIS, and 58 MLL), we also assessed mucin neovascularization on CD31 immunostains. On H&E-stained sections, neovascularization of mucin, defined as delicate, thin-walled microvessels in mucin, and unassociated with fibrous septae, was identified significantly more frequently in MC than in MLL (69.2% vs. 14.1%; P=0.0001). The difference in the frequency of mucin neovascularization between MC and MLL was even greater on CD31 immunostains (97.6% vs. 13.8%, P<0.00001). The sensitivity, specificity, positive predictive value, and negative predictive value of mucin neovascularization for categorizing a lesion as MC were 69.2%, 85.8%, 78.3%, and 79.2%, respectively, for H&E-stained sections and 97.6%, 86.2%, 83.7%, and 98.0%, respectively, for CD31 immunostains. We conclude that mucin neovascularization is significantly more common in MC than in MLL in breast CNB on H&E-stained sections and particularly on CD31 immunostains and may be a valuable adjunct in distinguishing between MC and MLL in problematic cases.

粘液癌 (MC) 和粘液囊肿样病变 (MLL) 之间的区别，特别是那些含有分离上皮碎片的病变，在乳腺核心针活检 (CNB) 提供的有限样本中可能存在问题。粘蛋白新生血管形成已被提议作为区分 MC 和 MLL 的标准，但其在帮助对 CNB 中产生粘蛋白的乳腺病变进行分类方面的价值尚未得到研究。为了解决这个问题，我们评估了 140 个含有产生粘蛋白的乳腺病变 CNB 的苏木精和伊红 (H&E) 染色切片上的粘蛋白新生血管形成，其中包括 52 个 MC、17 个产生粘蛋白的导管原位癌 (mDCIS) 和 71 个 MLL。在 116 例具有足够剩余材料的病例中（42 例 MC、16 例 mDCIS 和 58 例 MLL），我们还评估了 CD31 免疫染色的粘蛋白新生血管形成。在 H&E 染色切片上，粘蛋白新生血管形成（定义为粘蛋白中脆弱的薄壁微血管，与纤维隔膜无关）在 MC 中比在 MLL 中更常见（69.2% vs. 14.1%；P = 0.0001 ）。CD31 免疫染色显示 MC 和 MLL 之间粘蛋白新生血管发生频率的差异甚至更大（97.6% vs. 13.8%，P <0.00001）。对于 H&E 染色切片，粘蛋白新生血管将病变分类为 MC 的敏感性、特异性、阳性预测值和阴性预测值分别为 69.2%、85.8%、78.3% 和 79.2%，而对于CD31 免疫染色分别为 83.7% 和 98.0%。我们得出的结论是，在 H&E 染色切片上，特别是在 CD31 免疫染色上，在乳腺 CNB 中，粘​​蛋白新生血管在 MC 中比 MLL 中更常见，并且可能是在有问题的病例中区分 MC 和 MLL 的有价值的辅助手段。