Nail Tips For The Practicing Dermatologist

Nail expert Boni E. Elewski, MD, James Elder, MD, endowed professor of dermatology, University of Alabama, provided key nail tips for the practicing dermatologist to attendees at the Winter Clinical Dermatology Conference Hawaii in January 2015. This article highlights some of Dr. Elewski’s top nail tips in 4 categories: nail infections, inflammations, tumors and cosmetic issues.

Nail Infections

The green nail: Pseudomonas 

Pseudomonas favor moist, wet spaces. One way to prevent infectional recurrence is to keep the area dry. Vinegar soaks or vinegar drops can be used to eradicate Pseudomonas. Clorox bleach soaks can be used to bleach away the green color. Ciprofloxacin otic drops can also be ordered and patients should apply it under the nail. A course of oral antibiotics is an additional option. 

Two other things also are worth considering, says Dr. Elewski. First, conduct a fungal culture when the patient’s Pseudomonas is clear because dermatophytes are often there.1 In some cases, an x-ray can be done to rule out underlying osteomyelitis because the bone is directly beneath the nail plate, and bone infection can occur occasionally.


Today many options, including oral and topical options, exist for patients who have onychomycosis. “Of all the oral options, my personal favorite is fluconazole, for several reasons,” says Dr. Elewski. “I use fluconazole (Diflucan, Pfizer) 200 mg to 400 mg weekly. I like the long treatment duration. You have to treat until the nail is clear. This  takes a long time. Additionally, the slow growth of nail matches patients’ expectations. But I also like fluconazole because of all the oral drugs tested, even though this one is not FDA approved, it had the best cure rate.2” 

Other drugs available include itraconazole (Sporanox, Janssen Pharmaceuticals) and terbinafine (Lamisil, Novartis Consumer Health Inc.). Two recent topical solutions with a positive cure rate are also available: 10% efinacinazole solution (Jublia, Valeant Pharmaceuticals) and 5% tevaborole solution (Kerydin, Anacor Pharmaceuticals). Patients can apply the liquid solution under and around the nail. Because onychomycosis starts in the nail bed, the solution must reach the nail bed, under the nail. 

One patient who failed oral terbinafine had Trichophyton rubrum. He was ineligible for a clinical study for a topical antifungal because of severe onychomycosis, she explains. He was placed on the first topical drug (efinaconazole) when it became available. The patient applied under and around the nail. A yellow streak could be seen that went all the way to the cuticle. He also had dermatophytoma, or an abscess. After 3 months, a new nail began to grow and at 5 months, more new nail was present and the patient went on to clear with continued treatment.

Inflammatory Nail Disease

Nail psoriasis 

Eighty percent of people with psoriasis have nail psoriasis. It may be the only sign of psoriasis in 5% of people, notes Dr. Elewski. 

Three features are indicative of nail psoriasis. First, when nail pitting is present — a few pits or many pits — the patient probably has psoriasis (Figure 1). Second, oil spots are fairly pathognomonic of nail psoriasis but may be hard to recognize. Third, onycholysis with a red border is indicative of an inflammatory process, most likely psoriasis. 

Figure 1. Inflammatory nail disease, such as nail pitting, is indicative of psoriasis.


“A large list of entities (Table 1) can cause onycholysis without a red border. We see these every day in our practice. The tip is look for the red border,” she says. 

There are many non-specific clinical features of nail psoriasis (Table 2), including nail plate crumbling and complete dystrophy of the nail plate. With non-specific findings of nail psoriasis, the dermatologist must use other clues to rule it in or rule it out.  

When approaching dystrophic toenails, look at fingernails, she advises. “The typical features of nail psoriasis are more commonly seen in fingernails than toenails. When a patient comes to you with fingernail disease, look for psoriatic arthritis and ask about joint pain and morning stiffness. If the patient has psoriatic arthritis, their treatment might be very different than if they don’t,” she says.3,4 

“When a psoriatic patient comes to you with toenail disease keep in mind that patients may have both psoriasis and onychomycosis. In fact, about one-third of people have both.5,6 If you have abnormal toenails, and you have psoriasis, you have a third chance that your toenail also has a dermatophyte,” Dr. Elewski explains. 

Several topical treatments can be used for nail psoriasis. Topical steroids are frequently used. However, prolonged use of a topical steroid around the nail could lead to atrophy of the underlying phalanx, a condition known as disappearing digit.7,8 “The digit could start looking like a sharpened pencil, and it may occur in people of all ages,” she says, noting dermatologists should think about this before ordering prolonged steroids. 

Rotational therapy — steroid plus another treatment — in an alternating fashion is an option. Or a steroid alternate therapy could be tried first. For instance, some patients clear with the use of vitamin D ointment. 

Nail Tumors 


Erythronychia (red nails) maybe painful and is characterized by a longitudinal erythronychia (from the cuticle to the distal nail plate), which can be very subtle. “If you have it on one digit only, it is most likely a tumor, which probably needs a biopsy. If it’s on more than one digit, it’s probably an inflammatory process,” she says.

“The most common tumor is a benign process called an onychopapilloma.9 Other benign tumors, such as a glomus tumor, or a wart could also cause this, but malignant tumors can, too. Melanoma can cause erythronychia. So that’s something you need to consider, and consider a biopsy of the nail matrix,” she adds.


Melanonychia, also known as black nails, can present in a variety of ways. One presentation is longitudinal melanonychia. About 80% of African Americans may have this, also known as melanonychia striata. 

“Hutchinson’s sign indicates malignancy, and is periungual extension of the pigment,” she says. 

“The same rule applies as with erythronychia. If you have a patient with one, linear pigmented band, it could be a tumor. Be concerned about melanoma. A biopsy of the nail matrix can be done. If it’s multiple bands, it probably isn’t, particularly if the patient is a person of color.” 

She cautions that not all black nails are necessarily problematic. Other causes of acquired melanonychia include a patient with diffuse pigment on the nail plate. “If the patient has black fingernails look at the toenails. If the patient has normal toenails, it could be nail staining,” Dr. Elewski says. Hydroquinone, used frequently in bleaching creams, as well as vitamin C in cosmetics, can get on the nail and could lead to pigment in the nail plate. Hydroquinone is oxidized to a compound that is dark in color in the sun, and leads to a blackish pigment on the nail plate.

Other causes of nail pigmentation include medications (Table 3). Hydroxyurea is the most common drug that causes nail pigmentation. 

A patient with sickle cell syndrome, and who was treated with hydroxyurea had melanonychia in all nails (Figure 2). 

 Figure 2. A patient with sickle cell syndrome, and who was treated with hydroxyurea had melanonychia in all nails.

“Hydroxyurea is technically the most common in the literature, but in our practices as dermatologists, we might see more patients with minocycline. The thumb is the most commonly affected,” she says. “To determine if the melanonychia is external pigment or internal pigment, use a 15 blade and try to scrape off the black pigment. If it scrapes off easily, it’s probably external. If it doesn’t scrape off, then you have to start thinking of other things,” she advises.

Another clue: look at the toenails. If it is caused by something patients are putting on their face like hydroquinone, it is probably not getting on their toenails. Therefore, the toenails would be normal but their fingernails would not be. 

Beware of melanonychia-foolers such as Pseudomonas and Candida. “Pseudomonas sometimes has a greenish-blackish color. And Candida can cause a fungal melanonychia, which is usually in the lateral nail fold after a patient had paronychia from Candida. This can be treated with fluconazole orally once a week until the nail grows out. It could be greenish versus blackish. Before you call it green or black, look closely to be sure because dark green can look blackish in some patients,” she says.

Cosmetic Issues

Dry, brittle nails

 Dry, brittle nails are a common presentation and the standard of care is biotin at 3 mg to 5 mg per day. Patients can be advised to soak their nail in an inexpensive brand of olive oil and use emollient on their nails frequently. 

Two devices are also available for dry, brittle nails: a lacquer with chitin and a poly-ureaurethane solution. “The waterproof poly-ureaurethane solution works well, but patients should avoid applying it to the cuticle because it could cause dryness and irritation of the cuticle. The hydrosoluble lacquer can be used under nail polish. Washing may remove it, so you may have to reapply more often,” Dr. Elewski notes.


The onychogryphosis diagnosis can be a challenging one. Exclusion is helpful, according to Dr. Elewski. One way to differentiate it is there may be no tinea pedis. “If you determine the patient does have onychogryphosis, treat with urea 40% cream. It may have to be done under occlusion in some patients with onychogryphosis,” she says.  


Disclosure: Dr. Elewski has conducted clinical research for Amgen, Abbvie, Lilly, Merck, Novartis and Pfizer. She has been a consultant for Anacor, Novartis, Pfizer and Valeant. 


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