A 35 year old man comes to the GP because of a non healing sore on the vermillion of the middle of this lower lip. He has no history of major medical illnes and frequently goes bicycling. Physical exam shows a 1.5 cm raised lesion with an ulcerated surface and pale edge. Biopsy reveals malignant epithelial cells with accumulations of keratin. 1. What is the likely precursor to this lesion?

Connective tissue is the most abundant type of tissue in the body. It serves to connect and support other tissues and also has regulatory and immunologic functions. Connective tissue consists of cells, mainly fibroblasts, and an extracellular matrix (ECM).