A Guide To Detecting Nail Pathology

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Continuing Education Course #145 — September 2006

I am pleased to introduce the latest article, “A Guide To Detecting Nail Pathology,” in our CE series. This series, brought to you by the North American Center for Continuing Medical Education (NACCME), consists of regular CE activities that qualify for one continuing education contact hour (.1 CEU). Readers will not be required to pay a processing fee for this course.
Given that inappropriate management of nail unit dystrophy can arise from a lack of understanding of this clinical entity, Bradley W. Bakotic, DPM, DO, offers an insightful review of potential causes and contributing factors. Dr. Bakotic also provides a classification of types of nail unit dystrophy and insights on treatment. He also discusses the pros and cons of various diagnostic tests that are commonly used to augment the clinical diagnosis of onychomycosis.
At the end of this article, you’ll find a 10-question exam. Please mark your responses on the enclosed card and return it to NACCME. This course will be posted on Podiatry Today’s Web site (www.podiatrytoday.com) roughly one month after the publication date. I hope this CE series contributes to your clinical skills.

Sincerely,

Jeff A. Hall
Executive Editor
Podiatry Today

INSTRUCTIONS: Physicians may receive one continuing education contact hour (.1 CEU) by reading the article on pg. 77 and successfully answering the questions on pg. 82. Use the enclosed card provided to submit your answers or log on to www.podiatrytoday.com and respond via fax to (610) 560-0502.
ACCREDITATION: NACCME is approved by the Council on Podiatric Medical Education as a sponsor of continuing education in podiatric medicine.
DESIGNATION: This activity is approved for 1 continuing education contact hour or .1 CEU.
DISCLOSURE POLICY: All faculty participating in Continuing Education programs sponsored by NACCME are expected to disclose to the audience any real or apparent conflicts of interest related to the content of their presentation.
DISCLOSURE STATEMENTS: Dr. Bakotic has disclosed that he has no significant financial relationship with any organization that could be perceived as a real or apparent conflict of interest in the context of the subject of his presentation.
GRADING: Answers to the CE exam will be graded by NACCME. Within 60 days, you will be advised that you have passed or failed the exam. A score of 70 percent or above will comprise a passing grade. A certificate will be awarded to participants who successfully complete the exam.
TARGET AUDIENCE: Podiatrists.
RELEASE DATE: September 2006.
EXPIRATION DATE: September 30, 2007.
LEARNING OBJECTIVES: At the conclusion of this activity, participants should be able to:
• discuss how the pathogenesis of nail unit dystrophy and onychomycosis can affect diagnosis and management;
• describe the four types of nail unit dystrophy outlined by the author;
• assess the roles of onycholysis and microtrauma in causing nail unit dystrophy;
• discuss how onychomycosis can be complicated by superimposed microtrauma; and
• assess the strengths and weaknesses of diagnostic tests for onychomycosis.

Sponsored by the North American Center for Continuing Medical Education.

Here one can see “distal subungual” onychomycosis, which has probably developed as the result of precursory onycholysis.
Here is a view of hallux limitus with resultant traumatic nail unit dystrophy and early evolving onychomycosis.
This low power histopathologic image demonstrates the fine parakeratosis and acute inflammation within subungual keratin that is typical of psoriasis.
In this intermediate power histopathologic image, one can see haphazardly distributed melanin pigment within the substance of a nail plate that was thought to be mycotic. These features almost invariably represent changes induced by an underlying melanoma
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Author(s): 
By Bradley W. Bakotic, DPM, DO

   As all those who specialize in the treatment of lower extremity ailments will acknowledge, there is nothing uncommon about nail unit pathology. Though pristine appearing nail units are commonplace in children, advancing age may bring a combination of acute and chronic trauma, neoplastic processes, non-infectious dermatological diseases, and bona-fide mycotic and non-mycotic infections that take their toll. These stressors manifest as alterations in nail color, shape and/or texture.

   Too often in mainstream medicine, there is a tendency to attribute such changes within the nail unit solely to onychomycosis, leading clinicians to rely on oral or topical antifungal medications as “silver bullets” in their management. Such ill-fated reliance may lead to presumed drug inefficacy as even a perfect antifungal can only eradicate the organism if it is there. Often fungal infections are indeed present but represent a secondary phenomenon affecting a nail unit that was originally altered by a different pathologic process. In these cases, the best that one can hope for is a mycotic cure but a clinical failure.

   To fine tune our management of patients with nail unit dystrophy, we might benefit by viewing the problem as a constellation of several factors as opposed to equating nail unit dystrophy with onychomycosis. By assessing all the possible contributors to the nail unit abnormality, we will recognize the various processes that must be addressed in addition to, or in lieu of, antifungal therapy.

A Guide To The Pathogenesis Of Nail Unit Dystrophy And Onychomycosis

   Abnormal epithelial keratinization is the single most important process in the development of an overwhelming majority of nail unit dystrophy cases. The body’s outer surface, oral cavity, anus and vagina are covered by stratified squamous epithelium. The principal feature that distinguishes the skin of the body from the mucosa of the genital tract or oral cavity is surface keratinization or a stratum corneum. The surface skin requires keratin to protect us from water loss but the mucosa has no such requirement.

   This does not mean that the mucosa cannot become keratinized. In fact, stimuli such as persistent trauma, inflammation and exposure to the external elements routinely lead to mucosal keratinization as might various neoplastic processes. Classic examples of such abnormal keratinization include: that which occurs in the oral cavity in people who perpetually bite their inner cheeks or routinely dip tobacco; that which might occur in association with severe vaginal or uterine prolapse; or that which occurs naturally in circumcised men.

   Discourse on the topic of abnormal epithelial keratinization is pertinent to the subject of nail unit dystrophy for several reasons. Foremost, in the overwhelming majority of cases, nail unit dystrophy is the product of abnormal nail bed and matrical keratinization. It does not arise as the result of an abnormality in the nail plate itself. Unlike when keratinization occurs at exposed sites, when a stimulus leads to keratinization of the nail bed, the overlying (and usually unremarkable) nail plate serves as a barrier that prevents keratin from being sloughed and leads to its accumulation.

   Whether the stimulus is microtrauma, psoriasis, onycholysis, lichen planus or squamous cell carcinoma, nail bed keratinization may result in “dystrophic nails” that are clinically indistinguishable. It is only with some superficial patterns of onychomycosis not associated with nail bed keratinization and some cases of late stage total dystrophic onychomycosis (with florid infiltration of the nail plate itself) that one can make a diagnosis of “onychomycosis” with reasonable surety based on clinical findings alone.

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