Metastatic basal cell carcinoma with loss of p63 and mismatch repair proteins

BCC: basal cell carcinoma HH: hedgehog IHC: immunohistochemistry mBCC: metastatic basal cell carcinoma SUFU: suppressor of fused INTRODUCTION Basal cell carcinoma (BCC) represents nearly 80% of nonmelanoma primary skin malignancies in the United States. However, metastatic BCC (mBCC) is exceedingly rare, difficult to treat, and associated with high mortality, yet it’s easily preventable. We report a case of mBCC in a patient with a 15-year history of a neglected primary BCC on the left upper extremity. Mismatch repair protein expression was lost in the primary tumor and metastatic deposits. In addition, p63 expression, which was present in the primary BCC, was absent in the metastatic tumor cells.