Tag Archives: eczema

Why Do We Have Fingerprints?

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A patient of mine with severe hand dermatitis has an identity problem. She applied for a job that she is well qualified to get, except she doesn’t have any fingerprints. Her job requires a security clearance, and she has to have fingerprints to verify her identity (and to verify that she isn’t wanted in Montana). But her severe hand dermatitis has left her fingertips scarred, and she is unable to give adequate fingerprints.

Why do we have fingerprints in the first place? The ridges are unique and allow you to be distinguished from billions of other people. Although wonderful for the FBI, your fingerprints were never meant to assist in identifying you.

It has been traditionally thought that the tiny ridges increase the coefficient of friction of the skin making it easier to grasp and hold things. A smooth surface makes handling delicate objects like a dime, difficult, especially if your hands are wet.

New research suggests that the grooves have another, possibly more important function: they improve your sense of touch. Fingertips are exquisitely sensitive to touch. This is partly due to a special nerve called the Pacinian corpuscle. The tips of your fingers are packed with these sensitive receptors. One sensation that they are particularly attuned to is vibration. It turns out that the ridges on your fingertips when rubbed against an object create a  fine vibration that is not noticeable to you, but is detected by your Pacinian corpuscles.

Loss of fingerprints is uncommon. It can happen from trauma, as from a burn, or from chronic skin diseases such as eczema, psoriasis, or scleroderma. There are also rare genetic conditions such as dyskeratosis congenital, an inherited condition that leads to scaly skin and increased risk of skin cancers, where patients are born without fingerprints.

Excess inflammation, as from dermatitis or psoriasis, can sometimes lead to temporary changes in the fingerprints. These changes can be resolved with topical steroids or other systemic medications to treat the underlying condition. Once the fingerprint is scarred, however, there is no way to regenerate it.

Post written by Dr. Benabio Copyright The Derm Blog 2009

Photo: D. Sharon Pruitt (flickr)

Your Hands Are Teeming With Bacteria

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Right now your hands are teeming with bacteria. Countless trillions of organisms call your skin home, and that’s a good thing. Skin infections do not arise because you have bacteria on your skin. Rather, they arise because the type of bacteria on infected skin is not healthy bacteria but aggressive pathogenic bacteria.

Determining which bacteria are good and which are dangerous is difficult, but our immune systems have managed to get it right most of the time. When our immune systems are wrong, either an infection develops, or excess inflammation develops, as is the case in eczema or psoriasis.

Telling good from bad is hard. There are hundreds of types of bacteria on your hands right now. A recent study of college students (perhaps not the cleanest group of individuals) discovered that the average student has 140 different types of bacteria on his or her skin. There were over 4,000 different types of bacteria identified across all the students. Not surprisingly, the most common types were familiar household names: Propionobacterium (the bacteria responsible for acne), strep, and staph (of which the infamous methicillin resistant staph aureus, MRSA is a subtype).

There were also differences in the bacteria on the dominate hand versus the non-dominant hand — namely bacteria normally found in the gastrointestinal track was found more often on the dominant hand. This will no doubt lead to a follow up study of: “Do college students wash their hands before leaving the bathroom?” (Research so far does not look promising).

Photo: Pink Sherbert Photography (flickr)

Eczema and Asthma Link

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Eczema or atopic dermatitis is a common skin disorder seen mostly in children. It is characterized by a red, scaly, itchy rash that can occur on the face, neck, arms, legs, and sometimes the trunk.

We have known for some time now that eczema, also called atopic dermatitis, is also associated with asthma and allergic rhinitis (hay fever). At least 50% of children with severe eczema also develop asthma. Research from the Washington University School of Medicine might shed light on why these diseases go together.

The research, published in the journal PLoS, found that in mice, eczema-damaged skin produced a substance called thymic stromal lymphopoietin (TSLP). TSLP is a signal to the body that the skin has been damaged. When TSLP circulates through the blood, it elicits a powerful immune response. As such, TSLP is your skin’s way of warning you that its protective barrier has been breached and that backup defenses are needed to keep you protected.

Similar to your skin, your lungs are in direct contact with your environment as well, although we don’t often think of it that way. Like skin, lungs are exposed to the air with all its potential pathogens such as bacteria and viruses. It is not hard to see how an inflammatory disease that affects the skin might also affect the lungs. This is exactly what researchers found — when TSLP from the damaged skin traveled in the bloodstream to the mice’s lungs, it triggered inflammation in the lungs (similar to an asthma attack in humans). The researchers believe that TSLP is the link between eczema and asthma.

Ideally, if a drug was developed that blocked the production of TSLP, this might be a way to prevent people with eczema from developing asthma later in life. It also suggests that minimizing damage to the skin can help limit production of TSLP and improve both eczema and asthma.

Photo: Penreyes (flickr)

Roach Rash

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Cockroaches tend to get a bad rap. As repulsive an animal as they are to many people, the disease that they inflict on us is minimal compared to other insects like mosquitoes or fleas. In fact, although most dermatology books have whole chapters on insects that cause skin diseases, the infamous cockroach is rarely mentioned. Continue reading →