Predictors and outcomes of cutaneous metastatic breast carcinoma: a retrospective, single- institution review

Breast carcinoma is among the most common visceral malignancies to metastasize to the skin, but few studies have comprehensively characterized the patient and breast cancer-specific features of cutaneous metastases of primary breast carcinoma (CMBC). In this case control study, we identified key clinical, histopathologic, and molecular features of CMBC within a large, single-institution cohort. We further stratified between locoregional and distant cutaneous metastases to identify possible predictors of the eventual skin phenotype. Ninety-four (94) histologically confirmed cases of CMBC biopsied between January 2005 and December 2021 were identified via review of the University of Chicago Medicine pathology report database. Of these, 37 were locoregional and 57 were distant cutaneous metastases. The mean duration between diagnosis of breast cancer and CMBC was 7.02 years (range, 0–37 years). Histologically, most primary breast tumors were invasive ductal carcinomas (IDC; 82.2%). On subgroup analysis, older age and underlying invasive lobular carcinoma (ILC) were significantly associated with distant patterns of CMBC (P = 0.026 and 0.008, respectively). Notably, patients with distant CMBC also demonstrated worse functional status, more recalcitrant disease, and higher mortality than those with locoregional CMBC. Our analysis represents one of the largest cohorts to date of CMBC and highlights the importance of longitudinal skin surveillance in the detection of CMBC. Furthermore, our findings suggest that the primary breast cancer subtype may influence the eventual presentation of metastatic disease to the skin, a novel finding that warrants further exploration.