Expert Insights On Diagnosing Pigmented Skin Lesions

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Continuing Education Course #129 — April 2005

I am pleased to introduce the latest article, “Expert Insights On Diagnosing Pigmented Skin Lesions,” 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.

Malignant lesions arise more often in the foot than might be believed, making early recognition and a proper diagnosis vital. Bradley W. Bakotic, DPM, DO, draws upon clinical experience to detail the factors that may lead to a missed diagnosis of such pigmented lesions. He enumerates the telltale signs of atypical lesions and offers pointers on obtaining biopsies.

At the end of this article, you’ll find a nine-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: April 2005.
EXPIRATION DATE: April 30, 2006.
LEARNING OBJECTIVES: At the conclusion of this activity, participants should be able to:
• demonstrate an awareness of the prevalence of melanoma in the lower extremity;
• discuss factors that may lead to an incorrect or missed diagnosis of pigmented lesions;
• identify atypical pigmented lesions based upon their clinical chacteristics;
• list four key clinical characteristics of atypical pigmented lesions in the lower extremity; and
• cite the advantages of performing shave biopsies.

Sponsored by the North American Center for Continuing Medical Education.

Here one can see an early evolving melanoma in-situ (see the short arrow) arising in association with a benign superficial congenital nevus (see the long arrow).
Here is a malignant melanoma with a verrucous configuration. Note the digit-like projections of squamous epithelium.
Here is a compound congential nevus with irregular contours. Atypical histopathologic findings mandated a complete but conservative excision. (Photo courtesy of Horst Knapp, DPM)
Here one can see gentle grasping of the epidermal “lip” with forceps, repositioning of the scalpel to be relatively parallel with the surface epithelium and undermining of the lesion.
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Author(s): 
By Bradley W. Bakotic, DPM, DO

   During the course of a tightly scheduled office day, a 30-year-old female presents with a painful paronychia involving the lateral border of her right hallux. The painful nail border is acutely inflamed. The doctor temporarily defers a definitive chemical matrixectomy and opts to perform a “slant-back” procedure to remove the offending nail border.

   The doctor adducts the patient’s foot ever so slightly to access the problematic portion of the affected nail unit more easily. While doing so, the clinician notices a tan/brown, slightly elevated papule inferior to the lateral malleolus. The lesion is not particularly large (6 mm) and is of uniform color. However, it exhibits moderate asymmetry of shape. The patient says the lesion had been present her “entire life.” The physician removes the offending nail border and the patient goes home believing that her pedal problems are now resolved.

   This general scenario is not uncommon. The patient may be a 75-year-old man and the skin lesion may be a small scaly plaque, but the net result is often the same: an early evolving malignancy goes undiagnosed. Incidentally, the aforementioned 30-year-old woman was a real patient but, in this instance, the podiatric clinician insisted on performing a biopsy on the atypical lesion. The biopsy disclosed an early evolving melanoma.

Factors That Can Lead To Incorrect Diagnosis

   Readers might question how this could be possible. The patient (a young and competent historian) clearly stated the lesion had been there her entire life. This question leads us to the first important point: some melanomas arise in association with previously benign melanocytic nevi. Clinically atypical lesions must be subject to a histopathologic investigation. I have seen “well-intentioned” and competent clinicians who have been led astray and fell victim to “well-intentioned” and competent historians. This scenario is particularly common when dealing with geriatric patient populations. The simple fact is that melanoma may arise within longstanding, benign pigmented lesions on the skin, the skin of the foot not excluded. The history of longevity should not necessarily preclude obtaining a biopsy if one notes clinical atypia.

   A second point is that cutaneous malignancies are not “rare” in the skin of the foot as many of us were led to believe during our didactic years. Although malignancies related to sun exposure are less common on the foot, they may occur in this location. Melanomas arise in the skin of the lower extremity in 9 percent of cases within the Caucasian population and in half of all cases among African-Americans.1 Overall, as much as 15 percent of all melanoma is of the acral lentiginous type.2 Unfortunately, when melanomas arise on the skin of the foot, they do carry a poor prognosis largely due to delays in diagnosis.3

   If a podiatric physician does not routinely diagnose skin cancer in his or her patient population, it is probably not that he or she hasn’t seen cancer. Rather, it is much more likely due to missed diagnoses. In some cases, we are “bailed out” by other medical professionals who are in a position to make the diagnosis in our stead. However, in many instances, we are not. We must bear in mind that the skin of the foot is foremost the responsibility of the podiatrist and much of the medical community has grown to depend on podiatrists in this regard.

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