Twist1 in tumor cells and α‐smooth muscle actin in stromal cells are possible biomarkers for metastatic giant basal cell carcinoma

We previously reported a case of giant basal cell carcinoma (BCC) in a 75‐year‐old Japanese man, who subsequently developed a pulmonary metastasis. With regard to the pathogenesis of metastasis of BCC, recently, it has been reported that high levels of expression of Twist1 and N‐cadherin in primary and metastatic tumor cells, suggesting that Twist1 expression and an epithelial–mesenchymal transition (EMT) of tumor cells are important for the promotion of tumor invasion and subsequent metastasis. In this report, we identified the expressions of Twist1 in tumor cells and α‐smooth muscle actin (α‐SMA) in stromal cells in the primary and metastatic sites of giant BCC. These results suggest that Twist1‐induced EMT of tumor cells might have been associated with distant organ metastasis in our case, and the presence of α‐SMA‐positive myofibroblasts surrounding a BCC nest can be one of hallmarks of the aggressiveness of BCC.