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Health Matters: Mystery of the diseased toenail

It was a Thursday, another workday at the office. The first patient of the day was new to my practice, but presenting with a common complaint, that of thick, ugly fungal toenails. Do you suffer from such an affliction? Many do. Medically, there was nothing remarkable about this individual. Likewise, her foot health history: unremarkable, just the diseased toenails.

It sounds so simple. Over the last year, this individual had developed two diseased big toenails. They were uncomfortable at times, but never distinctly painful. Initially she had attempted treatment with an over-the-counter fungus medicine but saw little change. Her family doctor had prescribed a course of terbinafine, the most common oral agent prescribed for onychomycosis, but this also had produced no difference in the appearance of the nail.

She had subsequently sought the care of a dermatologist. This physician had prescribed, despite the inordinate expense, one of the new topical agents for nail fungus. The patient managed to obtain the medicine and used it faithfully as prescribed. Much to her dismay, its effectiveness did not match the medication’s cost and no real transformation was forthcoming. Understandably, my patient’s frustration was mounting, which brought her in to see me.

Experts in fungal disease recognize the difficulties in treating the resistant, disfiguring nail changes associated with this type of infection. One of the most challenging aspects of these is the diagnosis: people assume they know the cause. Obviously, her physicians had made assumptions regarding the diagnosis. Yet studies reveal only about half the time is the discoloration, the thickening, and the changes in shape, due to a fungal infection. To accurately ascertain the cause of your nail transformations, a specimen for biopsy must be obtained, which is sent to a specialized lab. This sometimes requires the use of a local anesthetic, but is the best way to get a definitive diagnosis.

As you may not have guessed, the individual in question was not diagnosed with onychomycosis (fungal nails) but psoriatic nails. Psoriasis is a chronic disease causing inflammation of various tissues, especially skin, resulting in the rapid overgrowth of skin cells. It is not due to an allergy or a “bad” diet. For this reason, it is not treatable with dietary changes. Although there is a strong genetic component, environmental factors are of critical importance. About 1 to 2% of the global population has some form of psoriasis, with considerable differences among regions and people of varying skin types. Neither gender nor race predilection appears to exist. Approximately half of those with psoriasis will exhibit nail alterations at some point.

Nail psoriasis causes changes to your fingernails and/or toenails. These changes are mistaken for a fungal infection far too often. Inappropriate, since they are treated very differently. One is an infection (and can spread), while the other is an autoimmune condition. The occurrence of psoriatic nail changes is indicative of a poorer prognosis overall. Nail psoriasis also portends a higher risk of developing psoriatic arthritis. Some common signs of nail psoriasis include the appearance of tiny dents in the nail (pitting), discoloration (white, yellow or brown), and nail separation, the lifting of the nail off the digit. My patient had all these changes, the classic three characteristics of the psoriatic nail.

A wonderful diagnostic tool I used in this patient’s case was a dermatoscope. Basically, it is a small, hand-held, very portable microscope. It allows the physician to easily observe microscopic changes of the skin, even into the skin. The benefits are innumerable and especially beneficial in podiatric medicine. My latest iteration is digital and plugs into the laptop, magnifying minute changes for all to see. (It can be quite a show.) Still, the gold standard in dermatologic medicine is histologic testing. The science of analyzing pathologic tissues has come so far, allowing us to learn so much from so little material.

Like skin psoriasis, nail psoriasis is chronic but may improve or worsen for no discernible reason. Trauma has a critical role in exacerbations and remissions of nail psoriasis. For example, because artificial nails increase mechanical stress to the nail plate, they will reliably worsen nail psoriasis. Those engaged in professions demanding significant use of the fingers will often experience an increase in the severity and frequency of psoriatic attacks. The same applies to any more physical means of employment, such as a job requiring the frequent pulling or pushing of heavy objects.

In most cases, nail psoriasis follows the skin changes of psoriasis and is therefore easy to diagnose. But in approximately five percent of cases, nail psoriasis occurs without the skin lesions and can pose a real diagnostic challenge, as in the case of our protagonist. This is especially true when alterations in the nail are atypical such as a single nail being affected. The analysis of a specimen by a pathologist, termed histopathology, is usually all that is necessary to make the diagnosis, provided the biopsy specimen is appropriately obtained.

Genes are the most important factor in an individual’s psoriatic manifestations. Many different genes contribute to psoriasis and how it develops in each sufferer, which partially explains the enormous variability in the response to treatment. Trauma is the most obvious causative agent other than genetic. Some of the identified risk factors for developing psoriasis include smoking, obesity, and alcohol use. Trauma to the nail unit will inevitably exacerbate the condition or induce recurrences.

The many treatments available give evidence that none is the ideal therapy. Nail psoriasis treatments require a long time, as the nail is a slow-growing skin structure. The effect of any nail treatment can’t be accurately evaluated before a year has elapsed, at a minimum. This is how long, on average, it takes for a big toenail to grow out and this length of time must pass prior to determining maximal improvement of any therapy. Additionally, excluding the presence of a fungal infection is a necessity when starting nail psoriasis therapy (as our patient discovered).

Nail psoriasis is highly resistant to almost all topical treatments, and thus this approach is less commonly used. The problem with all topical drugs is their limited penetration to the diseased tissue. As with fungal nails, reducing the barrier in some fashion increases the benefits of a topical. This can be achieved through nail removal, thinning of the nail, or drilling of small holes in the nail to provide better access of the medicine. As is often the case in these matters, topicals are nearly always safer. Those systemic therapies used to produce clearing of the skin are usually effective also in nail psoriasis. These can also be injected around the nail root, which largely avoids the systemic side effects.

Nail psoriasis can have a tremendous impact on many aspects of life for those afflicted. Need I say, the changes are negative ones, as a rule. With such a common problem (one out of every fifty people), one might hope there would be some semblance of a cure, but there is not. Surprisingly, nail psoriasis is only briefly mentioned in most guidelines on the diagnosis and treatment of psoriasis.

Truly, modern medicine has come so far, yet there is much we simply do not know. Still, there are treatments for controlling the signs and symptoms of this disease. Early and accurate identification is the key to proper treatment. Any therapy works better when it’s used on the appropriate condition. Get your nail changes looked at (REALLY closely) by a specialist. And get a biopsy. It only makes sense!

Editor’s note: Dr. Conway McLean is a physician practicing foot and ankle medicine in the Upper Peninsula, with a move of his Marquette office to the downtown area. McLean has lectured internationally on wound care and surgery, being double board certified in surgery, and also in wound care. He has a sub-specialty in foot-ankle orthotics. Dr. McLean welcomes questions or comments atdrcmclean@outlook.com.

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