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.