What are basal cell carcinomas?

Basal cell carcinomas (BCCs) are the most common cutaneous malignancy and outnumber squamous cell carcinomas by a 4:1 ratio. They are low-grade malignancies of the skin and are microscopically composed of basaloid cells with characteristic peripheral palisading of the nuclei. These basaloid tumor islands usually demonstrate connections to the overlying epidermis or follicular epithelium. BCCs are locally invasive tumors that rarely metastasize. The origin of these common tumors has been debated. The theory with the greatest supporting evidence is that BCCs originate from the follicular epithelium, specifically from the stem cells of the outer root sheath.

Donovan J: Review of the hair follicle origin hypothesis for basal cell carcinoma, Dermatol Surg 35(9):1311–1323, 2009.