Secondary Mucinous Carcinoma of the Skin: Metastatic Breast Cancer

BACKGROUND. Breast cancer is the most common cancer in women. Its involvement of skin is the most frequent of visceral cancers in women. In cutaneous metastatic disease, including breast cancer, the clinical and histologic pattern may be specific or nonspecific. Specific clinical patterns of cutaneous metastatic disease are linked with breast cancer but occur less often with other cancers metastatic to skin. Likewise, specific histologic patterns of cutaneous metastatic disease are linked with breast cancer but occur less often with other cancers metastatic to skin. OBJECTIVE. To present a case of a mucinous breast cancer metastatic to skin where the histologic pattern is similar to the primary tumor. METHODS. This is a case report and a literature review. RESULTS. Metastatic breast cancer may rarely resemble primary skin cancer, in this case primary mucinous carcinoma of the skin. We describe a 60-year-old woman with breast cancer with the incidental finding of a nonspecific, soft, solitary nodule on her back. It was found to contain mucinous material and on close examination was found to be a metastatic mucinous carcinoma of the skin from a primary adenocarcinoma of the breast. CONCLUSION. One usually considers that hard, firm nodules are more suggestive of cutaneous metastatic disease than soft, nondescript ones, but one should be careful to consider secondary mucinous carcinoma of the skin and a histologically similar solitary cutaneous metastasis.