Overview of Onychoscopy
Nail problems can sometimes signal skin diseases. While doctors can diagnose many of these diseases by examining the nails, sometimes this isn’t enough and they need more information. Although the best way to diagnose diseases of the skin is often through a biopsied sample examined under a microscope, carrying out a biopsy on a nail can be tricky for doctors and painful for patients.
For these reasons, a special technique known as onychoscopy, or nail dermoscopy, is often used. This involves examining the nail with a special tool that helps doctors see details they couldn’t see with the naked eye. This technique can help doctors diagnose a range of diseases without needing to carry out a biopsy and can also help them decide where to take a biopsy sample if one is needed.
Onychoscopy is used to look at parts of the nail that are normally hidden, like the nail bed and nail matrix. It was initially used to examine dark or discolored areas on the nails, but now it’s also used to diagnose other conditions, including diseases that cause inflammation or infection of the nails like lichen striatus (a skin disorder causing streaks on the skin), psoriasis (a skin disease characterized by red, itchy, and scaly patches), connective tissue disorders (illnesses that affect tissues binding parts of the body together), and onychomycosis (a fungal infection of the nail).
There are three main forms of onychoscopy: nonpolarized dermoscopy, polarized noncontact dermoscopy, and polarized contact dermoscopy. Nonpolarized dermoscopy is used first to detect surface changes in the nail, like ridges or roughness. Polarized noncontact dermoscopy (or dry dermoscopy) is used to examine deeper parts of the nail. Polarized contact dermoscopy (or wet dermoscopy), which involves applying a fluid between the lens of the onychoscope and the nail, is used to see more fine details of the nail.
While onychoscopy provides a lot of detail, it should be used alongside other methods of diagnosis. There are some challenges in using onychoscopy, such as the expense of equipment, required training, and lack of information about its use. Organizations like the International Dermoscopy Society and the Council for Nail Disorders are working to spread information about nail diseases and how they should be evaluated. For further information and training, have a look at their websites.
Anatomy and Physiology of Onychoscopy
The nail is a complicated system made up of different parts: the nail plate, nail matrix, nail bed, cuticle, and the surrounding skin. Understanding the structure and workings of the nail helps us to notice when it’s working as it should and when something is wrong.
Your nail includes many parts, such as the nail plate (the visible part and edge), nail bed, nail matrix, the folds of skin next to the nail, the cuticle, and the skin below the nail. The nail matrix is responsible for producing most of the nail. The lunula is the crescent-shaped white part of your nail often most visible on the thumb. The nail bed is the skin below the nail from the lunula to the end of the finger.
The blood supply to your fingers and toes is largely the same. Blood travels through arteries and veins, while tiny families of blood vessels, called glomus bodies help regulate temperature. For example, in the cold, these families of blood vessels can widen to make sure that blood still gets to your fingers or toes.
The area around the nail is served by the dorsal branches of matching digital nerves with the surfaces under your nail being served by corresponding nerves. This covers the soft tissue area at the end of your digit and extends up to the border of the nail.
Your nail plate is a changed layer of skin that’s made up of tightly packed, well-changed and flattened cells. The nail plate matrix has different types of skin with varying thickness with its cells often losing their nuclei to form parts of the nail, while vital cells have a fundamental role within the matrix. Your nail bed is made up of a layer of cells and a layer of fibers, while the skin folds around the nail resemble traditional skin and lack glands or hair follicles.
The hyponychium, the skin under the edge of the nail shows thick layers of skin, including cells responsible for forming parts of the nail.
Why do People Need Onychoscopy
When a person has issues with their nails, like unusual color, infection, inflammation, or injury, they may undergo an exam called onychoscopy. This procedure can also help diagnose other whole-body illness that show signs in the nails. Onychoscopy can help identify what’s causing a variety of nail problems.
When a Person Should Avoid Onychoscopy
Onychoscopy, which is a close examination of your nails, is safe for everyone. However, in instances where the nails are brittle or damaged, extra care should be taken. Also, one should stay alert when there’s a risk of spreading infections like COVID-19 during the check-up.
Equipment used for Onychoscopy
An onychoscopy is a medical procedure that examines the nails. This procedure involves the use of a special tool called a dermatoscope. Sometimes, items like alcohol wipes or a gel that helps improve visibility, like ultrasound gel, may also be needed.
Many of the latest models of handheld dermatoscopes are capable of changing between two settings: polarized and nonpolarized. If a dermatoscope can’t switch between these settings, specific ones for each function are available. Also, some dermatoscopes can be connected to digital cameras or mobile phones, allowing practitioners to take photos or record videos of the nails for further examination.
This tool helps doctors see changes or abnormalities on the nail plate (the hard part of the nail), such as dips, roughness, or diseases affecting the root of the nail (matrix). The doctor can see these best with noncontact onychoscopy, where the dermatoscope does not touch your nail.
On the other hand, contact onychoscopy (where the dermatoscope touches your nail) is best for seeing changes in the nail bed (the skin below the nail), color abnormalities, separation of the nail from the nail bed (onycholysis), and changes at the end of the nail. For the best view of your nail’s blood vessels during this procedure, your hand should be at heart level, and the temperature in the room should be average.
Who is needed to perform Onychoscopy?
Onychoscopy is a procedure where a special tool called a dermatoscope is used to examine the nails. This is often very helpful for doctors in fields such as skin care (dermatology), joint and muscle diseases (rheumatology), infectious diseases, and general health care (primary care). These doctors often deal with conditions that affect the nails. Any properly trained health professional, not just doctors, can use the dermatoscope to perform this procedure.
Preparing for Onychoscopy
Doctors use two types of skin examination tools, known as dermatoscopes, when looking at your nails. One tool uses normal light, while the other uses a special type of light called polarized light. These tools help doctors see your skin more clearly.
Sometimes, the surface of your skin can reflect the light from these tools, making it harder for the doctor to see. To solve this problem, they can use the dermatoscope at a different angle, use the one with polarized light, or apply a special gel on your skin.
There are several types of gels that doctors can use. Some are based on alcohol, water, or oil. However, doctors often choose a type of water-based gel known as ultrasound gel. This gel is good because it’s not too thick, so it stays in contact with the nail and fills any gaps. This makes it easier for the doctor to examine your nails.
While the doctor is examining your nails, it’s recommended that you keep your finger relaxed on a flat surface, without applying any extra pressure. This will ensure a successful and accurate examination.
How is Onychoscopy performed
Before the doctor can examine your nails, they need to be thoroughly cleaned. This involves washing your hands if they are visibly dirty, focusing on the nails. If necessary, the doctor may also use alcohol (or acetone in cases where nail polish is present) to ensure that your nails are as clean as they can be for examination.
The doctor will use a tool called a dermatoscope, which lets them take a close and detailed look at your nails. This tool needs to be adjusted and focused each time it’s used, according to the manufacturer’s instructions. The dermatoscope is usually held upright to examine the central part of the nail, but it might need to be angled to look at the edge of the nail. It will also be moved from side to side and back and forth so that they can see the whole nail, as it might not all fit in the viewing area at once.
The doctor will first examine your nails without touching them (noncontact onychoscopy). Following this, a special substance may be applied to your nails to make them more transparent and easier to examine (contact onychoscopy).
The dermatoscope works by using light in two different ways. When the light is non-polarized, it can better highlight irregularities on the surface of the nail such as pits and ridges. Whereas, when the light is polarized, it can ‘ignore’ any surface irregularities and provide a clearer view of the structures beneath the nail.
A special ultrasound gel can also be applied to your nail to help the doctor get a better view of the entire nail area. There’s also a technique called transillumination that can be used to work out how big a nail tumor is, like a glomus tumor.
In some cases, the doctor can use the dermatoscope to help guide a biopsy, if part or all of the nail needs to be removed for examination.
It’s standard procedure to start with a lower magnification for a general view before moving on to a higher level of detail, depending on what needs to be seen. It’s important to mention that the shape, size, and hardness of the nail can make these examinations challenging. But, don’t worry, your doctor is trained to handle it!
Possible Complications of Onychoscopy
Onychoscopy, a method used to examine nails, generally has very few issues. However, it’s important to make sure that the glass cover doesn’t pass germs from one patient to another, which could cause an infection. This can be easily handled by cleaning the lens with alcohol or using a disposable cover for the lens.
What Else Should I Know About Onychoscopy?
Onychoscopy is a useful tool that helps doctors examine your nails in a non-invasive way. It can assist in detecting various nail conditions early by identifying subtle changes in your nail structure. This can reduce the need for invasive procedures and help you get better sooner. Onychoscopy is used to look for issues like changes in pigmentation, infections, inflammatory diseases, conditions affecting the connective tissues, tumors, and injuries.
Pigmentation is a common issue checked through Onychoscopy. One type of pigment change is longitudinal melanonychia, where the pigmentation usually appears as a long strip in the nail. It can also appear sideways. Initially, it is evaluated if the pigment is due to cells called melanocytes (melanotic) or other factors like blood (non-melanotic). If it’s melanotic, the cause is either increased melanocyte activity or growth. Increased melanocyte activity is common in darker skin types, conditions like lichen planus, certain drug-related conditions, inflammation, injury, or benign pigmentary lesions. These appear as thin gray-colored bands.
Melanocyte growth often appears as a brown or black band. If it’s benign, it shows as a single band with color and thickness uniformity. Malignant growth, such as in nail matrix melanoma, often shows a brown or black band with irregular color, spacing, and thickness.
Non-melanotic pigmentation is often due to under-the-nail bleeding or infection. A blood clot under the nail looks like reddish-purple to black lesions. However, if it doesn’t go away, a wider range of causes, including melanotic pigmentation, should be considered. Certain infections can cause green or black pigmentation.
Leukonychia, or white nail discoloration, can manifest as true, apparent, or pseudo-leukonychia. In true leukonychia, the white pigmentation in the nail is due to changes in the nail’s keratinization processes. Apparent leukonychia has discoloration in the nail bed, while pseudo-leukonychia comes from external sources.
Onychoscopy can help diagnose nail infections, particularly onychomycosis, a common nail fungus. Onychomycosis shows as a whitish-yellow discoloration; dermoscopy shows striations in the nail from the free edge toward the proximal nail fold. Onycholysis, or a detached nail plate edge, is often seen in onychomycosis but may also be due to other causes like nail psoriasis and trauma.