The discoloration of one or several toenails can be a sign of a fungal infection. However, it is important to understand that there are other conditions that can lead to such changes, including dermatologic and systemic ones.
In this article, we will talk about the different color changes that can affect a person’s toenails, presenting the underlying conditions as well. Do not be in a rush to diagnose yourself and, upon noticing toenail discoloration, make sure to visit a specialist for an accurate diagnosis and treatment.
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White nails, the most common form of toenail discoloration
According to Text Atlas of Nail Disorders, white nails represent the most common form of toenail discoloration. When the nail plate is affected by the discoloration, the condition is known as true leukonychia.
On the other hand, if the subungual tissues are involved, we are talking about apparent leukonychia. In more severe cases, apparent leukonychia is accompanied by serious changes at the level of the nail matrix and bed, such as onycholysis and hyperkeratosis.
Last, but not least, there is pseudoleukonychia, in which the nails become white as a result of a fungal infection (most often).
In patients who suffer from true leukonychia, the toenails become opaque and white in color. The complete involvement of the toenail is rare, with only a part of the nail being affected in the majority of cases.
Depending on the underlying condition, such changes can either be temporary or permanent. As it was already mentioned above, pseudoleukonychia is most commonly caused by a fungal infection, the affectation being present at the level of the nail plate (superficial white onychomycosis).
It is possible that the frequent application of nail varnish, without removing previous layers, can cause similar problems.
It is important to understand that the color of the toenails can vary from one person to the other, being dependent on the underlying condition. Some patients present milky white toenails, while others present toenails that are chalky white or even with a bluish tinge. Ivory and porcelain white toenails are also possible, once again, depending on the dermatologic/systemic condition one is suffering from.
It is possible that the color of the toenails changes, as the underlying condition progresses. For example, patients who suffer from cholestatic jaundice might start out with white toenails. However, as the condition becomes severe, their nails might transition to a black color (in the distal nail plate area). Such changes are most often accompanied by a rapid growth of the affected toenails.
If only a part of the toenail is affected, this form is known as subtotal leukonychia. Such patients most commonly present a pinkish white arc in the distal part of the affected toenail, having a recent history of trauma or injury.
A particular form is transverse leukonychia, in which one or more toenails present a white, transverse band. This appears also as a direct result of trauma, affecting most commonly the distal part of the toenail. Transverse leukonychia is more common in children and young people, affecting the great toes and the second toe. Most patients who are diagnosed with this condition do not trim their nails short, the trauma being caused by the repetitive striking of the forefoot against the shoe. The condition can be easily solved by trimming the affected nails.
Patients who suffer from advanced liver disease, such as cirrhosis, can present white, opaque nails. In the medical field, these are known as Terry’s nails and they are used to confirm the progression of the condition. Severe forms of anemia can cause the toenails to turn a pale white color, suggesting that the hemoglobin levels have fallen significantly.
Melanonychia – brown or black nails
Melanonychia can either refer to the toenails turning a brown or a black color. While there are a number of conditions that can cause the toenails to turn such colors, the one that presents the biggest risks is malignant melanoma.
There are a number of elements that pinpoint the diagnosis into this direction, such as the fact that only one toenail is affected. The pigmentation can spread to the skin surrounding the nail; on the respective toenail, a band can appear, darkening in color and becoming wider as the condition progresses. Blurred borders also suggest a form of malignancy.
Before you despair, it is important to understand that there are other underlying conditions to take into consideration. Black nails are seen in people who have taken certain medication, as well as in those who are African American (without being pathologic).
The toenails can turn black in people who present naevi, in those who have suffered from trauma (due to subsequent hemorrhage), in case of fungal infections or as a result of exposure to silver nitrate.
A number of conditions can cause the toenails to turn brown in color. These conditions include but are not limited to: naevi, lentigo, Addison’s disease, haemochromatosis, malnutrition, thyroid disease.
Potassium permanganate, which is used as a disinfectant, can stain the toenails brown. Dark-skinned individuals, as well as Asians, can present brown toenails, without any pathology being involved. Medication can cause such color changes in a person toenails, with some of the most common drugs including: antiviral medication (acyclovir), tetracycline, ketoconazole, sulphonamides, cytotoxics and chlorpromazine (as presented in the Text Atlas of Nail Disorders). Pregnancy, smoking and tar are included among the potential causes of brown toenails.
A particular form is longitudinal melanonychia, in which a longitudinal black/brown band appears on the surface of the nail. This condition can be idiopathic or as a determinant of race but it can also be caused by a number of systemic conditions, such as Addison’s disease, secondary syphilis or vitamin B12 deficiency. Dermatologic conditions, such as lichen planus, fungal infections and bacterial infections can cause similar changes.
Other nail discolorations
The toenails can turn a yellow color in patients who have been diagnosed with fungal infections, the color change being accompanied by other symptoms (such as foul odor, brittle nails or purulent discharge). The yellow color of the toenails is also encountered in those who suffer from the yellow nail syndrome, those who consume high quantities of carotene or in those who have been diagnosed with liver disease & jaundice. It is important to understand and remember that medication can be a cause of yellow toenails. The drugs that can cause such problems include tetracycline, clioquinole, mepacrine and pencilliamine.
According to the Text Atlas of Nail Disorders , it is possible that the toenails present a discoloration that ranges from blue to grey. Such changes are encountered in patients who are treated with antimalarial medication but also in those who have been diagnosed with congenital pernicious anemia. Patients who suffer from Wilson’s disease can present such characteristic changes in their toenails, as well as those who are taking minocycline or phenothiazine.
One of the most common conditions in which the toenails turn a green color is the infection with aspergillus. Such characteristics changes are also encountered in patients who present the bullous disorders or in those who suffer from advanced liver disease, accompanied by jaundice.
A particular situation is represented by the infection with pseudomonas aeruginosa. The infection of the toenail starts at one side, the nail turning slowly a green color. Left untreated, the infection progresses, causing a greenish-black discoloration at the level of the affected nails. These will also thicken, with the infection penetrating into the cuticle. The infection with pseudomonas aeruginosa is particularly difficult to treat, as it rarely responds to current treatments. Moreover, in patients who have a weak immune system, such infections can be life-threatening.
Red & purple
Patients who suffer from congestive heart failure often present a characteristic discoloration at the level of their nails. The lunula turns a red color, suggesting the heart insufficiency. Such color changes are also encountered in patients who suffer from angiomas, different types of tumors or in those who are treated with heparin or warfarin. Lichen planus, systemic lupus erythematosus and porphyria can modify the color of the nails into red as well. Patients who are diagnosed with rheumatoid arthritis, alopecia areata or various types of cysts can present such color changes.
Diagnosis only made by a specialist
For a doctor, the color of the toenail(s) can be essential in making the right diagnosis. When visiting the doctor, he/she will take into consideration not only the clinical picture but also your family and medical history (for example, if there are cases of malignancy). Upon examining the aspect of the toenails, the doctor will recommend taking a small sample, in order to confirm the diagnosis (especially if there is an infection/malignancy suspected). When the diagnosis is confirmed, adequate treatment can be recommended.
As you have seen for yourself, toenail discoloration is a common occurrence, being either idiopathic, caused by medication or due to an underlying condition. The most important thing is that you do not try to diagnose yourself but rather visit a specialist and obtain the right diagnosis, as well as a suitable treatment.
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 A Text Atlas of Nail Disorders, Martin Dunitz, 2003. Retrieved from: http://www.rusmedserv.com/mycology/html/Atlas_of_Nail_Disorders.pdf