Although rarely metastatic, it can cause significant local tissue destruction and morbidity. Squamous cell carcinoma accounts for 20 percent of all cutaneous malignancies and can occasionally metastasize. It is fortunate that skin tumors, excluding melanoma, are the most amenable to curative therapy. Certain premalignant dermatoses that are described as cytologically malignant yet biologically benign may develop into malignant lesions.
Skin cancer appears frequently on sun-exposed areas, such as the face and the dorsa of the hands.
Its prevalence is great among outdoor workers, inhabitants of regions with a high level of annual sunshine, and persons with a fair complexion and blue eyes. Other etiologic factors include industrial exposure to pitch, tar, or tar products and ingestion of arsenic. Although arsenicals are rarely used in clinical medicine, environmental exposure to arsenic may occur through the use of certain herbicides or pesticides or from the ingestion of contaminated water from ground wells in certain parts of the world. Skin cancer may also occur as a late sequela to radiodermatitis, trauma, burns, scars, or chronic ulcers. Occasionally, it appears as a late manifestation of certain chronic infectious granulomatous diseases.