Melanonychia can be either the fingernails, or the toenails. Melanonychia is when your nails have darkened or become brown. The most common form of decolorization is a line that runs from the bottom to the top of the nail bed. It can appear on one or more nails.
If you have dark skin, these lines may be natural.
Whatever the reason, melanonychia can be a sign that you have other health problems. Melanonychia can also be known as melanonychia striata, or longitudinal melanonychia.
Melanonychia refers to a blackened or brownish discoloration of the nails. It can be longitudinal as shown here. This is where it runs along the length the nail. It may also run along the length of the nail, but it can also be diffused or transverse. Dermatology11/Shutterstock This is how brown longitudinal nail discoloration might look. Rytis Bernotas/Shutterstock Here’s what diffuse nail discoloration might look like. Science Photo Library / Alamy Stock Photo
There are two types of melanonychia.
- Melanocytic activation. It is an increase or deposits of melanin on your nails, but not an increase the number of pigment cells. It can also be caused by trauma, nutritional deficiencies, medication, or other factors.
- Melanocytic Hyperplasia. It is an increase of pigment cells in the nail bed. This growth can be benign, or malignant.
Melanonychia may appear on either fingernails and toenails. You may also see it on multiple nails at once.
It could look like this:
- A vertical black or brown stripe running the length of your nail
- A discoloration stripe of black or brown that is applied to the nails
- Nail deformity
Your fingers and toes are often translucent and not pigmented. Melanonychia occurs when melanin, a brown-colored pigment, is deposited into the nail by pigment cells called melanocytes. These deposits often form groups. The brownish or black stripe will appear as your nails grow.
Melanin deposits can be caused by two main processes.
You can cause melanocytic activation by:
- Racial differences
- carpal tunnel syndrome
- Nail biting
- Your shoes may rub against your feet because of a deformity in your foot
- Nail infection
- lichen planus
- viral warts
- skin cancer
- Addison’s disease
- Cushing’s syndrome
- growth hormone dysfunction
- Too much iron
- Exposure to X-rays
- antimalaria drugs
- chemotherapy drugs
The following could be the cause of melanocytic hyperplasia:
- Lesions (usually benign).
- moles and birthmarks are usually benign
- Nail cancer
You may also be affected by melanonychia from:
- Some bacteria
- hair dye
- Silver nitrate
The most likely to develop melanonychia are people of African descent. They are followed closely by people of darker skin colors.
After a series of tests, a diagnosis of melanonychia can be made. The doctor will conduct a complete physical examination of your toenails and fingernails. Your doctor will examine your nails to determine if they are deformed and how many have melanonychia. To determine if there are any medical conditions that could be causing melanonychia, your doctor will look at your medical history.
Next, a dermatoscopic exam is performed to examine the discolored areas. Your doctor will first look for signs that your melanonychia might be malignant.
Signs of nail melanoma could include:
- Discoloration that is greater than 3mil in width or has grown in size
- Brown pigmentation in irregular patterns
- Black or grey color together with the brown
- Pigmentation with granular appearance
- Nail deformity
Your doctor will not only look for signs of possible melanoma but also combine the findings of the dermoscopy with the physical exam to determine the type of melanonychia.
Your doctor may perform a nail biopsy after these steps. A biopsy is a procedure that removes small amounts of nail tissue and a portion of the nail. If there are any signs of cancer, this step will be performed in most cases. A biopsy is an important step to diagnose melanonychia. It will inform your doctor with certainty whether it is malignant or not.
Treatment for melanonychia depends on the cause. There is usually no treatment if melanonychia is benign and not cancerous.
Your doctor might change the medication you are taking to treat melanonychia. Or ask you to stop taking it for a while. Melanonychia is not a side effect of medication you can’t stop taking.
Other options for treatment depend on the cause. They may include:
- Antifungal or antibiotic medications should be taken if there is an infection.
- The underlying medical condition or disease that is causing melanonychia can be treated
Malignant melanonychia or cancerous areas must be removed. This could mean you lose some or all of your nails. Sometimes, the toe or finger with the tumor may need to be amputated.
Melanonychia can lead to nail cancer, bleeding under your nails, splitting your nail and nail deformity. Nail deformity can also be caused by a nail biopsy, which removes a small portion of the nail.
Most benign melanonychia has a good outlook and does not need treatment. It usually doesn’t go away on its own.
Malignant melanonychia has a less favorable outlook. Malignant melanonychia requires that the tumor be removed. This may include the need to amputation of your finger and/or toe. Because of its similarity to benign melanonychia, cancer of the nail can be difficult to detect in its early stages. Research found that a biopsy of most melanonychias is the best way for a quicker diagnosis.