Squamous carcinoma is manifested on the skin as a hard keratotic nodule or plaque. There is often a very adherent scale centrally with a hard rolled edge. It does not have the telangiectatic vessels or translucency of a basal cell carcinoma. There may be some associated inflammation. Squamous carcinoma can be clinically and histologically confused with benign keratoacanthoma.
Squamous carcinomas have a feeling of depth when palpated. While generally non-tender some can be painful to palpation.
Squamous carcinoma on areas of the skin that are moist, such as the lips, oral mucosa or vaginal mucosa, can be very white, secondary to the absorption of moisture.
Squamous carcinomas can develop from actinic keratoses or from dysplastic leukoplakia. They can also occur at the site of chronic irritation such as a chronic leg ulcer or old burn scar.