Diagnosing And Treating A Pigmented Lesion On The Hallux

Naohiro Shibuya, DPM, MS, FACFAS

   However, in general, melanomas found in the foot have a worse prognosis than melanomas in the rest of the body simply because they can advance undetected for a longer period of time. Therefore, I caution against generalizability of those randomized clinical trials to the foot melanoma.

   A biopsy is recommended when one is suspicious of melanoma. When lesions are small, an excisional biopsy with 1 mm of normal appearing border is recommended. When the lesion is large, a punch biopsy is recommended. The purpose of biopsy is not only to rule out malignancy but also to predict prognosis if the lesion is malignant. It is known that thickness of melanoma is highly correlated with the prognosis. Therefore, a full-thickness sample is necessary for the excisional or incisional biopsy to provide the depth of the lesion. A shave biopsy is usually not recommended.

   For more definitive treatment and excision of the lesion after an incisional biopsy if the lesion is malignant, one should excise the lesion with the recommended border size. The size of the border is dependent on the depth of the melanoma measured in the initial biopsy. If the thickness of the melanoma is less than 2 mm, excision of at least 1 cm of normal appearing border is recommended. If the lesion is more than 2 mm deep, a border of more than 2 cm is needed. In the foot and ankle, this often means some degree of amputation.

   Identifying depth and excising a lesion according to the guideline is important. However, clinicians should not overlook consulting an appropriate specialist, especially on high melanoma grade cases. Oncologists will normally follow the patient with a PET scan and/or sentinel biopsy depending on the melanoma grade.

   Dr. Shibuya is an Associate Professor of Surgery at the Texas A&M Health Science Center College of Medicine. He is the Acting Chief of the Section of Podiatry with the Central Texas VA Health Care System. He is on the staff with the Scott and White Health Care System. Dr. Shibuya is a Fellow of the American College of Foot and Ankle Surgeons.

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