Plantar warts diagnosed too often

Conway McLean, DPM

Missed diagnoses are a tremendous problem in modern medicine, and the statistics bear this out. Incorrect or inaccurate labels for various problems result in significant morbidity and mortality. Occasionally, it results only in treatment that is ineffective, allowing some chronic problem to continue, either causing lessened quality of life or perhaps reducing activity levels. Of course, for many seniors, this means less walking, eventually resulting in reduced cardio-vascular fitness, more arterial disease, and all the many ramifications, over time, of inadequate levels of exercise.

A common example would be the diagnosis of arthritis. Osteoarthritis is a common condition but, too often, the sufferer of a painful limb or body part is told simply “it’s arthritis”. A fait accompli, as though nothing can be done about it, and the pain must simply be lived with. On the contrary, many treatments are available to minimize joint degeneration, although the “holy grail” of medicine, the regrowth of cartilage, remains a work in progress.

Some missed diagnoses are more an inconvenience, as opposed to leading to any degree of debilitation. Any health care provider treating problems of the lower extremity has encountered an individual complaining of a small painful callus on the bottom of a foot. To the non-specialist, this may be labeled a simple callus and of no consequence. And it may be, but there are a plethora of other possibilities. From a plugged oil gland to skin cancer, many diagnoses are possible. Although some of these are statistically unlikely, no one wants to be a number, a statistic of the vagaries of nature.

A very common entity, a darkened, circular callus of the plantar surface (the bottom), most often is determined to be a wart (technically termed verrucae plantaris). And it may be, but plantar warts, although exceedingly common lesions, are just one of the many cutaneous (skin) conditions producing callus. As far as frequency, at least in the adult population, the aforementioned plugged gland is a more typical finding than a wart.

As most people know, warts are a skin infection, due to a virus. The Human Papilloma Virus (HPV for short) is the name for the type. Like many viral particles, it is transmitted by contact, not through air-borne transmission. Thus, stepping on a surface where these viral particles lie is frequently how the virus is picked up. Although these are fragile organisms, they can endure for longer in wet conditions. Consequently, the most likely location for someone to become infected is at a public pool or gym locker room.

It’s understandable that many confuse warts for some other problem. This is partly due to the proclivity of skin to produce callus when exposed to pressure. A bone which is out of position can lead to this callus-producing force but so can any type of mass in the skin layer. This may be a wart or any other growth forming in or under the skin. We all have thousands of oil and sweat glands in the skin and any one of these can get plugged up, creating pressure. Although this type of growth is deep to the skin, it will still produce pressure to the skin and result in callus. How to differentiate?

The definitive method of determining the specific cause of a callused skin lesion is a biopsy. When a callus is unusual in appearance or somehow atypical, this is the recommended approach. Not only can some skin cancers masquerade as verrucae, but long-standing warts in adults can even turn into a type of skin cancer. But generally-speaking, experienced doctors will recognize the signs and symptoms of a wart when it has the usual appearance, meaning a biopsy isn’t considered a requirement.

To a treating physician, as well as those afflicted, warts are a frustrating problem. They are infamous for their persistence and high rate of recurrence. Too often, regardless of the method of treatment, the mass comes back. Yet this is quite logical because of how viruses infect skin: they take over individual skin cells. If just a few infected cells remain, the wart will return, even though the skin may look normal.

Another interesting fact is their volatility in children. Their immune systems are quite different than adults and warts noticeably more unpredictable. Whereas in adults, a wart can remain stable and unchanging for years, a verrucae may suddenly disappear in a child, practically overnight. On the other hand, one lesion can turn into 10, seemingly in the space of a day.

Warts can be painful, simply because of the pressure exerted on deeper tissues. Obviously, this will depend on their location. Their resistance to treatment can also be chalked up to the critical force of weight bearing: pressure pushes the growth into the foot. In effect, the majority of it is hidden, inaccessible, and so, better protected. Contrast that with a wart on a finger, which is much easier to treat.

Treatment methods abound for verrucae plantaris, which is more a testament to the mediocre success rate of all of them. Conservative methods revolve around physically destroying the infected skin, or, in essence, poisoning it. Multiple examples of both categories can be found. Application of an acid is the typical home method and works moderately well when the wart is exposed, as it would be on a finger. When the wart is not, as is the case when on the bottom of the foot, a better topical method is a substance that causes a blister to form. The idea is that the wart will be part of the blister and can be safely trimmed away.

Surgical methods don’t have a significantly higher success rate, but when they do succeed, surgery at least requires only one visit. The most common procedure involves cutting the wart out, yet if the bottom layer of skin is penetrated during the procedure, scar tissue will form. But this is a scar you will be walking on the rest of your life, and that can be a painful thing. Another surgical technique involves repeatedly penetrating the wart with a device producing high intensity radiowaves. This has the advantage of not producing a hole in the skin, so it entails a more comfortable recovery.

Some bizarre new methods are being attempted, including the injection of a fungus, or topical application of an oral contraceptive. Interestingly, a procedure once considered highly experimental is becoming more commonplace, in which one of the warts is buried under the skin. This apparently triggers the immune system to recognize the wart as foreign tissue.

Although they continue to be an extremely common problem, warts are not a truly dangerous health issue. Although there are potential complications, the most significant result is decreased activity levels. That means a reduced quality of life, as well as decreased cardio-vascular fitness. And that can be serious. So have the chronic callused spot on your foot checked out; it may be a wart, or it may something else. Know what you are dealing with, then find out how best to treat it. An important rule in medicine: an accurate diagnosis means more effective treatment.


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