7 skin conditions that could indicate a more serious problem

Our skin acts as somewhat of a window into our body, often reflecting many internal conditions that would otherwise be invisible to us. A surprising number of medical conditions can manifest with complications, reactions, or symptoms on the skin. While it would be impossible to compile a list of every skin symptom of every internal problem, here are seven key skin changes that may be an early sign of serious health conditions.

Did you know? The skin is our body's largest organ.

1. Itching

Uncontrollably itchy skin can be a sign of Hodgkin lymphoma, a type of cancer that affects white blood cells. But don't worry - itchy skin can also be caused by many health conditions other than cancer, including dryness, allergies, bug bites, dermatitis, chickenpox, psoriasis, ringworm and shingles. A long-term itch that just won't go away could be a sign of diabetes, kidney or liver disease, or HIV.

Did you know? An itchy spot on your skin can also be a symptom of skin cancer. A new or changing spot (including a spot that starts to itch or irritate you) is usually one of the first symptoms people notice. If you see any changes in your moles, see a skin cancer doctor for a skin check as soon as you can.

2. Patches of thicker, darker skin

Hyperpigmentation - or darkening of the skin occurring patchily on some parts of your body - can be a condition called acanthosis nigricans, which can be a symptom of diabetes. It usually occurs in the skin folds, typically on the back of the neck and in the creases of the arms. This symptom is especially common in kids. Note that hyperpigmentation can also occur in completely healthy people and is not always a cause for concern.

3. Warm, sweaty skin or cold, dry skin (or thinning hair)

An over- or under-active thyroid can change the way your skin feels. The thyroid is a butterfly-shaped gland in the neck that releases hormones to regulate metabolism, heart rate, and body temperature. In people with an over-active thyroid, too much thyroid hormone is produced, which can manifest in increased sweating and warm, moist skin; it can also result in thinning of the hair. In people with an under-active thyroid, too little of the hormone is produced, resulting in cold, pale, rough and dry skin; these people can also experience patchy hair loss on the outer third of their eyebrows.

4. Darkening skin

People with Addison's disease may experience darkening of the skin in a way that makes them look tanned. In Addison's disease, the adrenal glands don't produce enough hormones cortisol and aldosterone, making the skin more pigmented and resulting in severe symptoms including fatigue.

5. Sensitivity to the sun

Sun sensitivity is one of many different skin symptoms that could indicate lupus, a condition in which the body's immune system attacks its own organs and tissue. About half of people with lupus experience sun sensitivity. Rashes are also an indicator of the disease, especially a "butterfly rash" - so called because it spreads across both cheeks in a butterfly shape. Mouth ulcers can also be a skin sign of lupus.

Did you know? The mucous membrane inside your mouth is considered part of your skin.

6. A tender bump under the skin

Inflammatory bowel disease, including Crohn's disease and ulcerative colitis, can manifest with specific skin symptoms including something called pyoderma gangrenosum - eroded lesions that form on the legs and don't heal. Another skin symptom of inflammatory bowel disease is the formation of tender, red bumps under the skin.

7. A rash on the hands

Dermatomyositis is a less common autoimmune disorder that can cause both muscle weakness and distinctive skin issues, including a rash called Gottron's papules that can appear on the back of the hands. Another is called the shawl sign: a red rash that covers the shoulders, arms and upper back in a pattern resembling a shawl.

If you have any moles, spots or lesions that are new, changing or concerning, it could be skin cancer. Book in for a professional skin cancer check at least once a year for the utmost peace of mind.

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Written by National Skin Cancer Centres