2023-05-06 00:30:14
Nail melanonychia can have multiple causes, from infections to tumors. Therefore, it is essential to make an adequate differential diagnosis.
‘Nail melanonychia’ is a term used to refer to the dark pigmentation of the nails, both on the hands and feet. In certain people it is a physiological trait, but it can also be the symptom of an underlying health problem.
In particular, it has been linked to melanoma, bacterial or fungal infections, or other skin diseases. Hence the need to investigate its cause in order to avoid serious complications. How to identify it? In the following space we will tell you more about its symptoms, diagnosis and possible treatments.
What is nail melanonychia?
Nail melanonychia is a condition of the nails. These are convex and semi-transparent structures located in the distal part of the fingers. They are made up mainly of dead cells that contain keratin, a fibrous protein that gives them firmness and resistance.
Physiologically, there is no melanin in the nails. This is the substance responsible for skin pigmentation. What happens in nail melanonychia is that melanin causes discoloration of the nails because it occurs in them.
It may appear as a single dark band or streak on the nail plate. In other cases, it spreads throughout the structure, causing discoloration throughout the piece. Its appearance is usually brown or black. In addition, it can appear on one or more nails.
Symptoms of nail melanonychia
The main clinical manifestation of nail melanonychia is the appearance of a longitudinal brown, black or grayish band. This usually starts in the matrix, but extends towards the end of the nail plate. In rare cases, it involves the entire nail or originates as a transverse band.
According to information from Dermatology Research and Practice, the dark coloration is due to an increase in the number and function of melanocytes. The latter are the cells that are responsible for synthesizing melanin.
When the color is gray, the cause is hyperpigmentation of the epithelium.
It is possible that the nail also presents various colors and that the lines that make up the nail melanonychia are wide. Also, if the cause is a malignant tumor, other serious symptoms may occur, such as:
- Nodules.
- Ulcerations.
- Nail dystrophy.
- Surrounding skin involvement.
- Pain (rare cases).
Types of nail melanonychia
Depending on the discoloration of the nail, different types of nail melanonychia are distinguished. Let’s see:
- First of all, we find longitudinal or striated melanonychia. It’s the most frequent form. In this case, only a long longitudinal band is produced along the length of the nail.
- The second type is diffuse or total melanonychia. What happens is that the discoloration affects the entire nail plate.
- Finally, can be transversal. The colored line crosses the nail transversely.
What are your causes?
Nail melanonychia occurs due to an increase in the number of melanocytes or their activity. That is, it occurs when there is a production of melanin above normal.
- An increase in the number of melanocytes in the nail is called ‘melanocytic hyperplasia’. This condition can be benign, but in some cases it also has malignant features.
- When it occurs due to increased melanin production, it is called ‘melanocytic activation’.
However, there are many pathologies or situations that can lead to nail melanonychia. We explain them to you in the following sections.
infections
Certain infections, both fungal and bacterial, can cause nail melanonychia. Some fungi are capable of producing melanin, which is incorporated into the nails. It is more frequent that it occurs in the feet, since they are subjected to humidity in a more continuous way.
Some bacterial infections, typical of people with a weakened immune system, give rise to this fact. For example, infection by Pseudomonas. Even, It can be seen in people with the human immunodeficiency virus.
Injuries and skin conditions
Blows to the hands or nails can cause nail melanonychia. The same is true of many skin diseases. This pathology has been described in the context of psoriasis, lichen planus, or amyloidosis.
Systemic diseases and pregnancy
There are certain diseases such as Addison’s disease or Cushing’s syndrome, that can cause this condition. The same happens with some vitamin deficiencies, such as vitamin B12 deficiency. Malnutrition has also been linked.
Although it is not a disease, it has been seen that pregnancy is a stage in which the incidence of nail melanonychia increases. In fact, in this case it is common for several different fingers to be affected.
Medicines
Some drugs, especially those used for chemotherapy, can cause melanonychia. It is one of the causes most related to transverse bands in the nail.
tumors
Tumors, both benign and malignant, can cause nail melanonychia. For example, Squamous cell carcinoma is one type of cancer that can cause it. The same occurs with acral lentiginous melanoma. It is a rare type of melanoma, rare, that affects the nails.
Lentigo is another associated benign condition, as is nevus of the nail matrix. The latter is the most common cause of melanonychia in children. It is characterized by the presence of ‘nests’ of melanocytes. That is to say, by accumulations of the same in the affected place.
Risk factor’s
Nail melanonychia can occur in people of all ages and races. However, it most often affects African-Americans and Japanese. So much so that it is estimated that its incidence is greater than 75% in African-Americans and that it can reach 20% in Asians.
However, this condition is rare in the Caucasian race. The most affected skin types, according to Fitzpatrick’s classification, are V and VI.
On the other hand, age can also be considered a risk factor; It is seen especially in people over fifty years of age.
Other associated factors have to do with the work environment. The people that work in continuous contact with water or moist substances are more likely to develop nail melanonychia due to infections.
The same is true if you are frequently exposed to trauma. Whether it is when working, doing certain sports activities or any other action, blows can lead to melanonychia.
Diagnosis and treatment of nail melanonychia
The diagnosis of nail melanonychia can be complex. In some cases it is enough to analyze the symptoms and have an obvious trigger, such as a blow. However, in many other patients it is necessary to resort to complementary tests to achieve a definitive diagnosis.
The most widely used test is biopsy.. It consists of extracting a sample of the affected nail and analyzing it in the laboratory. The objective is to rule out whether it is a malignant pathology such as melanoma. It is essential to perform it in cases of sudden onset or a history of it.
The treatment of nail melanonychia will depend on what its cause is. If it is a benign process, it is likely that there is no need to intervene in any way. However, if it is something malignant, surgery may be suggested. The surgical procedure can be based on removing the nail or even the finger.
What you must remember
Nail melanonychia is a pathology that consists of abnormal and dark pigmentation of one or more nails. This condition can be due to multiple causes, both benign and malignant. For example, it can be a symptom of a melanoma.
Thus, It is essential that in the face of this sign you always consult a doctor. Making an early diagnosis can considerably improve the prognosis by being able to establish early treatment.
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