Solid Papillary Carcinoma of the Breast: Magnetic Resonance Mammography, Digital Mammography, and Ultrasound Findings

Spectrum of Mucin-containing Lesions of the Breast: Multimodality Imaging Review with Pathologic Correlation

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.

Papillary lesions of the breast: a review

Papillary breast lesions are rare breast tumors that comprise a broad spectrum of diseases. Pathologically they present as mass-like projections attached to the wall of the ducts, supported by fibrovascular stalks lined by epithelial cells. On mammogram they appear as masses that can be associated with microcalcifications. Ultrasound is the most used imaging modality. On ultrasound papillary lesions appear as homogeneous solid lesions or complex intracystic lesions. A nonparallel orientation, an echogenic halo or posterior acoustic enhancement associated with microcalcifications are highly suggestive of malignancy. MRI has proven to be useful to establish the extent of the lesion. Core needle biopsy is the gold standard for diagnosis. Surgical excision is usually recommended, although treatment for papillomas without atypia is still controversial.

A review of mucinous lesions of the breast

Mucinous lesions of the breast include a variety of benign and malignant epithelial processes that display intracytoplasmic or extracellular mucin, including mucocele-like lesions, mucinous carcinoma, solid papillary carcinoma, and other rare subtypes of mucin-producing carcinoma. The finding of free-floating or stromal mucin accumulations is a diagnostic challenge of which the significance depends on the clinical, radiologic, and pathologic context. This article emphasizes the differential diagnosis between benign and malignant mucin-producing lesions, with a brief consideration of potential mimics, such as biphasic and mesenchymal lesions with associated with mucinous, myxoid, or matrix material.