Squamous cell carcinoma of the nose. This skin cancer can develop from<unk>  if they are not treated. Untreated<unk> s follow one of three paths: they can either persist as<unk> s, regress, or progress to invasive skin cancer, as<unk>  lesions are considered to be on the same continuum with squamous cell carcinoma (SCC).<unk>  lesions that regress also have the potential to recur. * Progression: The overall risk of an<unk>  turning into invasive cancer is low. In average-risk individuals, likelihood of an<unk>  lesion progressing to SCC is less than 1% per year. Despite this low rate of progression, studies suggest that a full 60% of SCCs arise from pre-existing<unk> s, reinforcing the idea that these lesions are closely related. * Regression: Reported regression rates for single<unk>  lesions have ranged between 15–63% after one year. * Recurrence: Recurrence rates after 1 year for single<unk>  lesions that have regressed range between 15–53%. Clinical course Given the aforementioned differering clinical outcomes, it is difficult to predict the clinical course of any given<unk> .<unk>  lesions may also come and go—in a cycle of appearing on the skin, remaining for months, and then disappearing. Often they will reappear in a few weeks or months, particularly after unprotected sun exposure. Left untreated, there is a chance that the lesion will advance to become invasive. Although it is difficult to predict whether an<unk>  will advance to become squamous cell carcinoma, it has been noted that squamous cell carcinomas originate in lesions formerly diagnosed as<unk> s with frequencies reported between 65 and 97%.
Actinic keratosis
Squamous cell skin cancer
Hydrocarbon keratosis
Arsenical keratosis
Reactional keratosis
Seborrheic keratosis
Smokeless tobacco keratosis
PUVA keratosis