CME ArticleHistologic Patterns of Cutaneous Metastases of Breast Carcinoma: A Clinicopathologic Study of 232 CasesRonen, Shira MD*; Suster, David MD†; Chen, Wei-Shen MD, PhD‡; Ronen, Natali MD§; Arudra, Sri Krishna C. MD¶; Trinidad, Celestine MD‖; Ivan, Doina MD**; Prieto, Victor G. MD, PhD**; Suster, Saul MD†† Author Information *Staff Member, Department of Pathology, Cleveland Clinic Foundation, Cleveland, OH; †Assistant Professor, Department of Pathology, Rutgers University, New Jersey Medical School, Newark, NJ; ‡Assistant Professor, Department of Dermatology and Cutaneous Surgery, University of South Florida, Tampa, FL; §Pathology Resident, Department of Pathology, Medical College of Wisconsin, Milwaukee, WI; ¶Staff Member, Department of Pathology, Sandford Hospital, Bismarck, ND; ‖Staff Member, University of Santo Tomas, Espana, Manila, Philippines; **Professor, Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX; and ††Professor, Departments of Pathology, Medical College of Wisconsin, Milwaukee, WI. Correspondence: Saul Suster, MD, Professor of Pathology, Medical College of Wisconsin, 9200 W. Wisconsin Avenue, Milwaukee, WI 53226 (e-mail: [email protected]). V.G. Prieto has disclosed that he was a consultant for Myriad Genetic Laboratories/myPath Melanoma. Lippincott CME Institute has identified and resolved all conflicts of interest concerning this educational activity. All other authors, faculty, and staff in a position to control the content of this CME activity and their spouses/life partners (if any) have disclosed that they have no financial relationships with, or financial interests in, any commercial organizations relevant to this educational activity. Presented in part at the United States and Canadian Academy of Pathology annual meeting; March 21, 2018; Vancouver, BC, Canada. Work by S. Ronen, W.-S. Chen, S. K. C. Arudra, and C. Trinidad was performed in the department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX. The American Journal of Dermatopathology 43(6):p 401-411, June 2021. | DOI: 10.1097/DAD.0000000000001841 Buy CME Test Metrics Abstract Cutaneous metastasis may be the initial sign of internal malignancy but more often represents a late manifestation of widely disseminated disease. Breast carcinoma is the most common malignancy to metastasize to the skin. Although several studies have detailed the histopathologic patterns of cutaneous metastasis from internal malignancies, very little has been published regarding metastases of breast carcinoma to the skin. Furthermore, the histopathologic and clinical features observed in the cases of breast carcinoma with local skin involvement as opposed to cases exhibiting distant cutaneous metastases have not been adequately investigated. We have reviewed 232 cases of breast carcinoma with cutaneous metastases from 2 large institutions. All cases of carcinoma of the breast with involvement of the skin of the anterior chest wall were compared with those with distant cutaneous metastases. Two hundred thirty-two cases in 199 patients were included, of which 126 had skin involvement exclusively involving the ipsilateral anterior chest, and 106 had biopsy-proven distant cutaneous metastases. Twelve patients had both local and distal spread. Distant cutaneous metastases showed a predilection for the contralateral anterior chest wall area, followed by the head and neck, back, and abdomen. Histologically, most of the tumors presented in this series showed features of infiltrating ductal carcinoma. In both ipsilateral and distant metastases, the tumors demonstrated little change in histologic features from the primary lesion; however, the distant metastases showed a tendency to display more poorly differentiated features. The mean patient survival when cutaneous involvement was localized to the skin of the anterior chest wall was 23 months as compared with 20.6 months when distant sites were affected. A comparison of the clinicopathologic features of the patients presented in this series suggests that alternate biological mechanisms may apply for local and distant skin metastases from breast carcinoma. Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.