Evaluation of PRAME Expression in Cases of Breast Carcinoma Metastatic to Skin

Cutaneous metastases of breast neoplasms indicate advanced disease with poor prognosis. The role of Preferentially Expressed Antigen in Melanoma (PRAME) expression in breast cancer skin metastases remains poorly understood. In this study, we investigate PRAME expression in breast carcinoma metastatic to the skin, particularly triple-negative breast cancers (TNBC). A retrospective review of breast cancer cases with skin metastasis was conducted from January 2005 to March 2023. PRAME immunostaining was performed on skin metastatic lesions and corresponding primary tumors. A comparison group of noncutaneous metastases (n = 11) was included. Thirty patients with cutaneous metastasis were identified (29 women, 1 man; mean age 63 years). The most common site of skin metastasis was chest (25 cases, 83%). Histologically, 25 cases (83%) were invasive ductal carcinoma. Eleven cases (37%) were TNBC. PRAME positivity was observed in 10 skin metastases (33%) with 70% being triple negative. Among 20 available primary samples, only 3 were PRAME positive with corresponding positive metastases. Comparison group showed minimal PRAME expression. In total, 40% of patients died, with TNBC associated with higher mortality ( P = 0.04). All PRAME-positive TNBC patients with follow-up were deceased. In conclusion, PRAME expression occurred in approximately one-third of breast cancer skin metastases, with predominance in triple-negative breast cancer. These findings warrant further investigation of PRAME's role in cutaneous metastasis and its diagnostic implications.