Sarcomatoid transformation of a basal cell carcinoma following treatment with hedgehog inhibitors.

Vismodegib and sonidegib are sonic hedgehog inhibitors (SHHIs) available for the treatment of advanced basal cell carcinoma (BCC). Cases of sarcomatoid differentiation during treatment of BCC with SHHIs have not been previously reported. We present a unique case of a locally advanced BCC that underwent sarcomatoid transformation, manifesting as a large mass complicated by local invasion and lung metastases, following treatment with sonidegib.