• The two black arrows point towards the edges of the tumor.

• The tumor has caused a large ulcer in the skin.

•There is a strong association with exposure to the sun.

•Direct damage to DNA by UV radiation.

•Basal cell carcinomas are common lesions particularly in older light-skinned individuals.

•Most common non-pigmented skin carcinoma.

•Basal cell carcinomas occur on the face and are overall more frequent in men in most locations, except the legs where they occur more frequently in women.

•They are usually present as small bumps or lumps, often with some evidence of ulceration.

•They are slow-growing tumors that can be locally invasive and destructive, but usually do not metastasize to distant sites and are non-lethal.

•However, if allowed to go for long periods of time locally, they can be locally destructive and if around the eye or ear may invade into the brain.

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•Grossly, they are pearly white nodules of varying size, often with a central area of ulceration and telangiectatic blood vessels around them.

•Histologically, they are composed of small cuboidal cells with vesicular nuclei and basophilic cytoplasm.

•The distinctive feature of a basal cell carcinoma is the presence of these cells that resemble the normal basal cells of stratified squamous epithelium.

•A characteristic feature that distinguishes them from squamous cell carcinomas is the absence of a stratum spinosum, or spiny cell layer.

•This feature becomes particularly important in those basal cell carcinomas that show significant keratin formation.

•Basal cell carcinomas can undergo significant cystic change in the center.

•Another characteristic feature of basal cell carcinomas is the tendency of cells in the periphery to line up with their nuclei with the long access perpendicular to the basement membrane and approximately parallel to each other.

•This structure is known as "palisading".

•The nests also artifactually separate from the stroma, so called "cracking".

• Robbins and Cotran: Pathologic Basis of Disease, 7th ed., 2005, pp. 1242-4.

• Harrison^s Principles of Internal Medicine, 16 th Edition, 2005, Ch. 73.

• Current literature from PubMed at National Library of Medicine