Dermatologic manifestations of internal cancer.

The cutaneous manifestations of internal cancer can develop either before or after the presence of an underlying tumor has been established. These signs may result either from the physical presence of tumor cells in the skin or from presumed metabolic effects of tumor cells located at visceral sites. Occasionally, skin involvement in cancer patients is biologically unrelated to the tumor but is instead part of a well-defined inherited syndrome featuring an increased incidence of internal cancer. Whatever the association, inspection of the skin remains an essential part of the complete physical examination.