In general terms, newly formed rashes, abnormal growths, dermal discolorations and changes in skin texture may be caused by a serious underlying disease, according to the American Academy of Dermatology. Jaundice, darkening or reddening of the skin, severe itching and excessive hair growth may indicate the presence of a malignant tumor in the body, as stated by the American Cancer Society. Early detection and treatment of these symptoms may arrest further development of the illness.
Typically, unusual changes to the skin are manifestations that internal conditions within the body are not optimal. A rash forming on the lower limbs and feet that is unresponsive to topical medications, such as creams, ointments and gels, is commonly associated with hepatitis C. Drug reaction with eosinophilia and systemic symptoms, or DRESS syndrome, is linked to rashes that develop due to an adverse reaction to certain medicines. Consulting a dermatologist is highly recommended for this condition.
The formation of yellow or oily skin breakouts may signify increased triglyceride levels due to diabetes. Skin tumors may also signal hereditary disorders. Darkening and bronzing of the skin may indicate Addison's disease and iron metabolism disorders, respectively. The latter may progress and cause the liver to lose its functionality. Inflammations where hardening of the skin ensues can be early signs of systemic sclerosis. Lymphoma and multiple myeloma are closely related to a disease that is indicated by a doughy skin complexion.