This large, crusted tumor on the temple has clinical features of both squamous cell carcinoma (scaly crust), and basal cell carcinoma (translucency in some areas). Histologically, it also has features of both, hence the name basosquamous. These lesions have a biological aggressiveness intermediate between basal cell and squamous cell carcinomas. They are also called keratotic basal cell carcinoma, squamous cell carcinoma with basaloid differentiation, basal cell carcinoma with squamous differentiation, or "collision tumors." This lesion was treated by Mohs surgery.
