Basal cell carcinomas, like squamous cell carcinomas of the skin, belong to the non-melanotic (light, white) skin cancer. Basal cell carcinomas develop from cells in the so-called basal cell layer of the skin and the root sheaths of the hair follicles. They occur most frequently in the head and neck area, less frequently on the torso, arms or legs. In contrast to malignant melanoma, black skin cancer, basal cell carcinomas rarely form secondary tumors (metastases) in other organs. However, the tumors can grow aggressively into the surrounding tissue, also affecting cartilage and bone.