A 53 year old man presents with a longstanding history of a 1cm lesion on his arm. It has started bleeding on touch. What is the most likely diagnosis?

The key is D. Squamous cell carcinoma. [SSCs Arises in squamous cells. SCCs may occur on all areas of the body including the mucous membranes and genitals, but are most common in areas frequently exposed to the sun, such as the rim of the ear, lower lip, face, balding scalp, neck, hands, arms and legs. SCCs often look like scaly red patches, open sores, elevated growths with a central depression, or warts; they may crust or bleed. A tissue sample (biopsy) will be examined under a microscope to arrive at a diagnosis. Squamous cell carcinomas detected at an early stage and removed promptly are almost always curable and cause minimal damage].