By Cindy Owen, MD, FAAD
Assistant Professor of Dermatology, University of Louisville
Dermatologists find that the skin offers a window to what is going on inside the body, and changes to the skin may signal a more serious health problem. The key is knowing how to spot these early-warning signs so that the internal disease can be successfully treated before it becomes a bigger problem.
Common Signs Spell Internal Trouble
In some cases the skin can show signs of an internal disease before the disease advances and becomes more serious; in other cases a symptom is noticeable on the skin long after the disease begins causing damage internally. There are hundreds of nuances of the skin that could spell trouble, but a handful of general skin changes commonly signal an internal disease.
- An unusual rash or a rash that does not respond to treatment or is accompanied by fever, joint pain, muscle aches, or other symptoms could indicate an internal problem or infection.
- A rash occurring on the tops of the feet and the lower legs that does not respond to topical steroids or antifungals can be a sign of hepatitis C infection (necrolytic acral erythema).
- Occasionally, people develop a rash due to an allergy to a new medicine. It is important to carefully monitor such a rash because it could be a sign of a more serious condition known as DRESS syndrome, which stands for drug reaction (or rash) with eosinophilia and systemic symptoms. This condition can occur weeks to months after the start of a new medication, making it very difficult to diagnose. This is a potentially serious medical condition that could involve inflammation of the liver, heart, lungs, or thyroid. It is important to see a dermatologist for proper diagnosis if a rash is accompanied by fever, swelling of the face or lymph nodes, or a feeling of illness.
- Dermatomyositis is an inflammatory muscle disease with notable skin changes and, in up to 20 percent of cases, is associated with a wide variety of internal cancers (ovarian cancer being the most common in women). Signs on the skin include a violet-colored rash on the upper eyelids and in areas that are exposed to sunlight as well as raised, scaly bumps on the knuckles. Other skin changes can be seen on the nail folds, with visible blood vessels and ragged-looking cuticles that appear thicker and separate from the nail. In one case with only subtle changes of the nail fold and cuticles, a patient was diagnosed with dermatomyositis before being diagnosed with an early-stage, treatable kidney cancer.
- Any new growths should be checked thoroughly by a board-certified dermatologist because they could be skin cancer. Rarely, new growths can represent a metastasis, or spread, of an internal cancer to the skin. Also, certain tumors of the skin can be a sign of internal disease or a genetic syndrome.
- In one example, yellow or waxy-looking bumps on the arms, legs, or trunk (eruptive xanthomas) could indicate high triglyceride levels, often a sign of uncontrolled diabetes. In these instances a biopsy in conjunction with laboratory testing can lead to diagnosis and treatment, hopefully reducing the cardiovascular risk from these conditions.
- Skin color changes can be a sign of internal disease. In the most common example, yellowing of the skin can indicate liver disease. Other skin color changes can be important signs as well, including darkening of the skin.
- Noticeable darkening of creases in the skin, sun-exposed areas, joints, and old scars could be a sign of adrenal disease, such as Addison’s disease.
- Bronzing of the skin in a patient with diabetes can be a sign of an inherited defect in iron metabolism that leads to liver failure known as hemochromatosis.
Change in Texture
- Any unusual softening or hardening of the skin could indicate an underlying medical problem.
- Systemic sclerosis is an autoimmune disease in which one of the early signs is swelling, followed by hardening of the skin. In more severe cases, it could result in hardening of internal organs, such as the lungs or heart.
- Acanthosis nigricans is a common condition seen in overweight patients that results in darkened, velvety skin occurring in skin folds and most commonly on the back of the neck. The appearance of this textural change in the skin could indicate the presence of early diabetes. In some cases this skin change may be a sign of a cancerous tumor in an internal organ.
- Acquired cutis laxa is a rare connective tissue disease marked by very loose or doughy-feeling skin that is silky to the touch. This disease could be a sign of lymphoma or multiple myeloma, and it could advance to involve loss of elasticity of internal organs. With proper diagnosis, it is possible to slow the progression of the disease.
When examining a patient’s skin for signs of skin cancer or any type of skin condition, dermatologists are always mindful of unusual markings on the skin that could indicate another medical problem. Dermatologists have expertise to know when signs on the skin are more than a skin problem, which is why it is important to see a board-certified dermatologist if you notice any skin changes. Doing so can ensure proper diagnosis and in some cases stop the progression of a more serious medical condition.
Headquartered in Schaumburg, Illinois, the American Academy of Dermatology, founded in 1938, is the largest, most influential, and most representative of all dermatologic associations. With a membership of more than 17,000 physicians worldwide, the academy is committed to advancing the diagnosis and the medical, surgical, and cosmetic treatment of the skin, hair, and nails; advocating high standards in clinical practice, education, and research in dermatology; and supporting and enhancing patient care for a lifetime of healthier skin, hair, and nails. For more information contact the academy at (888) 462-DERM  or visit aad.org. Follow the academy on Facebook (American Academy of Dermatology) or Twitter (@AADskin).
Be Your Own Skin Detective
People can be their own best detective in noticing unusual changes in their skin. See a dermatologist as soon as possible in these instances:
- You notice an unusual rash that can’t be attributed to a specific cause.
- A rash is diagnosed but not responding to the prescribed treatment.
- A rash is accompanied by fever, muscle aches, or other unusual symptoms.