Recognizing Amelanotic Melanoma In The Lower Extremity

Author(s): 
Bryan C. Markinson, DPM, FASPD

Case Study Five: Is The Keratotic Lesion A Wart Or Something Else Entirely?

In 2007, a very active 82-year-old female heard from a pedicurist that she had a wart on her heel and that she should see a podiatrist, which she did immediately. The podiatrist noted a keratotic lesion that resembled a wart but he was suspicious about it. Although the lesion had no pigment suggestive of melanoma and was not ulcerated, he decided that the appearance was not typical of a wart and performed a biopsy. The diagnosis was minimally invasive amelanotic melanoma.

   Upon referring the patient to me for definitive care, the treating podiatrist was unable to be more specific about what made him suspicious. The patient underwent wide excision with a skin graft along with sentinel lymph node biopsy (see above photo). Preoperative PET scanning was negative. She started on interferon therapy but discontinued this due to side effects. She soon completed a more personalized course with dosing spaced out to help minimize side effects.

   Interestingly, the patient recently underwent a follow-up PET scan (scheduled annually since her surgery) to search for signs of metastatic disease from the original tumor. There was a positive finding in one lower lung lobe, which turned out to be a primary lung malignancy. This was caught early and was totally resectable. As far as melanoma goes, she remains free of any evident disease.

In Summary

It only takes a brief review of the literature to realize that all forms of melanoma may present with amelanotic variants and may even masquerade as other lesions, even other tumors that do not rise to the level of urgency that melanoma does. This of course contributes to diagnosis at later stages of the disease. An additional complicating factor is that very often the history of the lesions may support another diagnosis such as trauma or foot ulcer. In the other extreme, there may be a rapidly developing process, from days to weeks, culminating in ulceration, bleeding and toenail lysis.

   We must be proactive in the early diagnosis of melanoma in all of our patients. (See “A Suggested Protocol For Obtaining Biopsies Of Lesions” at right.) The best way to do this is to set out on any one day and actively screen all patients for skin lesions to the level of the tibial tubercule, whatever the chief concern articulated by the patient. I am virtually certain that very soon, less than a few days even, you will come across lesions that cause some concern or doubt, and must, at a minimum, undergo histologic diagnosis. Whether you do the biopsy yourself or get a dermatology consult, you will be elevating your standard of care and saving lives for sure.

   Dr. Markinson is the Chief of Podiatric Medicine and Surgery in the Leni and Peter W. May Department of Orthopedic Surgery of the Mount Sinai School of Medicine in New York City. He is also an instructor in the Department of Dermatological Surgery at the Mount Sinai School of Medicine.

   Dr. Markinson is a Fellow of the American Society of Podiatric Dermatology. He is board certified by the American Board of Podiatric Orthopedics and Primary Podiatric Medicine.




Comments

The literature states that melanoma in the foot is rare for a specific reason: feet have been neglected by "regular" doctors. Since podiatry has shifted into the surgical realm, I suspect that the incidence of melanoma in the foot will rise.

Be prepared to be removed from the course of treatment if a malignancy is detected. No matter how credentialed a podiatrist you might be, there is no place in the regimen of care rendered to the melanoma patient but for reassurance.

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