ARRS 2022 Abstracts

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E1672. Non-Mammary Metastases to the Breast and Lymphoma of the Breast: Everything the Radiologist Needs to Know
Authors
  1. Ruskin Cua; Department of Radiology, Keck School of Medicine
  2. Lawrence Wei; Department of Radiology, Keck School of Medicine
  3. Tejas Manchandia; Department of Radiology, Keck School of Medicine
  4. Linda Hovanessian-Larsen; Department of Radiology, Keck School of Medicine
  5. Sandy Lee; Department of Radiology, Keck School of Medicine
Background
Non-mammary metastasis to the breast is relatively rare; however, it is usually associated with a poor prognosis. The overall incidence ranges from 0.3–2%, with numbers varying based on inclusion or exclusion of patients with leukemia and lymphoma. Aside from breast cancer and lymphoproliferative disease/lymphoma, melanoma and lung cancer are the most common primary malignancies to metastasize to the breast. Most reported cases of non-mammary metastases to the breast occur in young women, possibly due to the role of estrogen in increasing overall vascularity of the breast. Because of their similar imaging appearance, it is often difficult to differentiate metastatic lesions in the breast from primary breast cancers or benign lesions and confirmation with tissue sampling is needed. Another less common but increasingly recognized entity is breast implant associated anaplastic large cell lymphoma (BIA-ALL), which has its own characteristic imaging features. Furthermore, there may be some confusion in characterization of non-mammary metastases as they pertain to the Mammography Quality Standards Act (MQSA) audit.

Educational Goals / Teaching Points
The goals of this exhibit are to review epidemiology, imaging features, diagnosis, treatment, and prognosis of hematogenous and lymphatic metastasis to the breast, primary and secondary lymphoma of the breast and axilla, and breast implant associated anaplastic large cell lymphoma (BIA-ALL). We present multimodality imaging case examples and review current literature and mammography audit for non-mammary breast neoplasms.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Non-mammary metastases may be detected on screening or diagnostic mammography. Their imaging characteristics are similar to that of primary breast malignancy, often presenting as a high density mass, round or oval in shape, with circumscribed or microlobulated margins, typically without associated calcifications. Their typical sonographic features include round or oval shape with hypoechoic echo pattern. Posterior acoustic enhancement is common in these masses with posterior acoustic shadowing less commonly seen. Non-mammary metastases are also commonly initially identified on CT given the increasing amount of CT examinations being performed. Lymphoma of the breast usually presents as a single mass to the breast without a known extramammary lymphoma and may also present with local inflammatory signs. BIA-ALL is intimately associated with a history of textured implant (saline or silicone) with late peri-implant effusion being suspicious in that setting.

Conclusion
Familiarity of both non-mammary metastasis to the breast and lymphoma of the breast is critical to guide patient diagnosis and care. Thorough knowledge of both entities is essential for any radiology trainee and breast radiologist to ensure appropriate clinical management.