乳腺含粘蛋白病变涵盖多种良性和恶性过程。组织学表现包括偶然出现的充满粘液的良性囊肿或导管、粘液囊肿样病变 (MLL)、产生粘蛋白的导管原位癌和浸润性粘液癌。 MLL 的特征是存在含有粘蛋白的囊肿，通常与外渗的基质粘蛋白有关。 MLL 通常是良性的，但可能与上皮异型性或恶性肿瘤有关。粘液癌代表乳腺粘液性病变谱系的恶性末端。循证文献支持对无相关异型性或恶性肿瘤的良性 MLL 采取保守治疗，对表现出此类病理特征的病变保留切除。 MLL 最常见的影像学表现是乳房 X 光检查中的微钙化。没有特定的影像学特征可以预测手术切除时的恶性结果。根据世界卫生组织的标准定义，浸润性粘液癌是一种异质性乳腺肿瘤亚型。粘液癌分为纯亚型（>90% 粘液成分）或混合亚型（10%-90% 粘液成分）。除少数例外，纯粘液癌通常具有良好的预后和生存率。混合性粘液癌没有同样良好的预后，而是与无特殊类型的浸润性乳腺癌相似。可以根据其粘液性和非粘液性内容物来识别粘液癌的特征性诊断成像特征。 ©RSNA，2023 本文提供在线补充材料。本文的测验问题可通过在线学习中心获得。

Mucin-containing lesions of the breast encompass a wide range of benign and malignant processes. The spectrum of histologic findings includes incidental mucus-filled benign cysts or ducts, mucocele-like lesions (MLLs), mucin-producing ductal carcinoma in situ, and invasive mucinous carcinoma. MLL is characterized by the presence of mucin-containing cysts that are typically associated with extravasated stromal mucin. MLL is often benign but can be associated with epithelial atypia or malignancy. Mucinous carcinoma represents the malignant end of the spectrum of mucinous lesions of the breast. Evidence-based literature supports a conservative approach for benign MLLs without associated atypia or malignancy, reserving excision for those lesions exhibiting such pathologic features. The most common imaging finding for MLL is microcalcifications at mammography. No specific imaging feature is predictive of malignant outcome at surgical excision. Invasive mucinous carcinoma is a heterogeneous breast tumor subtype, as defined according to the World Health Organization criteria. Mucinous carcinomas are categorized into pure (>90% mucinous component) or mixed (10%-90% mucinous component) subtypes. Pure mucinous carcinomas are generally associated with excellent prognosis and survival, with a few exceptions. Mixed mucinous carcinomas do not have the same favorable prognosis and instead behave similarly to invasive breast carcinomas of no special type. Characteristic diagnostic imaging features can be identified for mucinous carcinoma based on its mucinous and nonmucinous contents. ©RSNA, 2023 Online supplemental material is available for this article. Quiz questions for this article are available through the Online Learning Center.