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Raising And Addressing Questions About Recent Dermatology Feature Articles
In the February 2020 article, “A Stepwise Approach To Evaluating And Managing Longitudinal Melanonychia," the author cites literature that indicates use of the dermoscopy tool to determine what lesions to biopsy. When I encounter a patient with suspicious pathology that warrants a biopsy, lack of use of dermoscopy places me in a disadvantageous position with potential liability should litigation result. Why would Podiatry Today publish this?
For podiatrists, any diagnosis achieved without using dermoscopy as standard of care may place doctors in compromised positions. I am anxious to have malpractice insurance carriers weigh in.
-Clifford Wolf, DPM
Oceanside, Calif.
It is difficult to know what Dr. Wolf is objecting to from his communication. In no way did my article suggest that dermoscopic examination was a standard of care in the evaluation of any lesion. In my opinion, there should be more concern about NOT learning this technique than about getting sued for not using it.
This article was about longitudinal melanonychia. In this specific instance, training in and developing expertise in dermoscopy will enable the practitioner with high degrees of certainty to determine if the lesion is suspicious for melanoma of the nail matrix and deserving of biopsy.
Since only one to three percent of these lesions are the result of melanoma, it makes sense to employ the technique to reassure patients that the lesion can be observed for change. The same is true for volar pigmented lesions.
Dermoscopy is quite easy to learn. One should make the decision to biopsy on a constellation of findings, which can include the results of dermoscopic examination. Not doing dermoscopy has not put podiatrists in compromised medicolegal positions. As performance and outcomes measures will be increasingly more important in the current medical landscape, dermoscopy offers the opportunity to be cost-effective, not to mention being a more astute clinician.
- Bryan C. Markinson, DPM
New York, N.Y.
Debating The Diagnosis Of Dystrophic Toenails
In the October 2019 article, "Keys To Diagnosing And Treating Dystrophic Toenails," M. Joel Morse, DPM presents an overview of treating dystrophic toenails. However, I am challenging a couple of his published statements.
In discussing the diagnostic workup for patients with dystrophic nails, Dr Morse wrote "... PAS, PCR and cultures are not always accurate and may be cost-prohibitive.” This statement is very misleading and perpetuates a false narrative regarding diagnostic testing. Periodic acid-Schiff (PAS) and polymerase chain reaction (PCR) are incredibly accurate for identifying onychomycosis and are complementary tests as PAS is very sensitive toward diagnosing onychomycosis and microtrauma while PCR (DNA testing), based on my experience, is the single best laboratory test to identify the causative genus and species for onychomycosis.
However, fungal culture is vastly inferior as it requires approximately one month for results and has a statistically significant high rate of false negatives.1 Dr. Morse also neglected to mention the added benefit of using Gomori Methenamine Silver (GMS) stains, especially for geriatric patients, as GMS identifies decayed fungus better than PAS.2
Regarding the cost of diagnostic tests, if you read the article in question, Dr. Morse only states PCR is cost-prohibitive without providing any proof or references, even though there are many inexpensive PCR tests (such as COVID-19, etc.) and ones for onychomycosis. Dr. Morse should realize that any discussion about costs is highly subjective and regional in nature. Additionally, he demonstrated research bias as he failed to mention the cost of the other diagnostic modalities in his article such as biopsy, surgical avulsion, X-ray and MRI.
Dr. Morse also stated, "Toenail onychomycosis accounts for approximately 50 percent of nail onychodystrophy" and did not provide a reference. However, in my personal research of over one million toenail specimens submitted by podiatrists over a 10-year period to Bako Diagnostics, I have discovered that approximately 63 percent of onychodystrophy involves onychomycosis. I personally believe that the true number is much higher (70 to 75 percent) as many podiatrists submit distal nail clippings without including diagnostic proximal subungual debris.
Respectfully,
William P. Scherer, DPM, MS, DABFAS
Senior Podiatric Medical Advisor, Bako Diagnostics
Delray Beach, Fla.
References
- Gustafson E, Bakotic W, Bennett L, Page L, McCarthy L. DNA-based detection for onychomycosis correlates better to histopathology than does fungal culture. Dermatol Online J. 2019;25(7):1-9.
- D’Hue Z, Perkins S, Billings S. GMS is superior to PAS for diagnosis of onychomycosis. J Cutan Pathol. 2008;35(8):745-747.
In regard to Dr. Scherer’s letter, he took my statement about the accuracy and costs of PAS, PCR and cultures out of context. The sentences in my article were as follows:
“Onychomycosis also has distinct features dermatoscopically, including a spiked pattern, longitudinal striae, linear edges and distal irregular termination. This is helpful as PAS, PCR and cultures are not always accurate and may be cost-prohibitive.”
I reviewed the dermatoscope as a diagnostic tool and mentioned that some of the tests are costly. Tests are not always 100 percent accurate so the dermatoscope aids in that diagnosis. I was not trying to disparage lab tests.
Dr. Scherer claims I demonstrated research bias because I did not mention the cost of other modalities such as biopsy, surgical avulsion, X-ray, and MRI. He is missing the point. Medical care and diagnostic tests are expensive but are very helpful and the best way to find the cause of a problem. However, if a patient does not have insurance or cannot pay for the desired test, the next best thing is diagnostic observation: using one’s own eyes and brain to come up with a working diagnosis.
There is a cost to all laboratory tests but that is not the point. In regard to the other tests mentioned by Dr. Scherer, clinicians usually do not use biopsy for onychomycosis, except in cases of single nail dystrophy. Surgical avulsion is not a test. Clinicians generally do not use X-ray to diagnose onychomycosis but they may use it to rule out an exostosis, again, in single nail dystrophy. Podiatrists never use MRI for the initial diagnosis of onychomycosis. The least expensive test is using one’s diagnostic acumen.
Dr. Scherer rightly notes that I left out a reference. This was inadvertent and the reference should be: Gupta AK, Versteeg SG, Shear NH. Onychomycosis in the 21st century: an update on diagnosis, epidemiology, and treatment. J Cut Med Surg. 2017;21(6):525-539.
- M. Joel Morse, DPM
Washington, D.C.
