Malignant Melanoma on the Sole: How to Detect the Early Lesions Efficiently

Early detection of malignant melanoma (MM) is essential to improve the prognosis. In non-white populations, including Japanese, the sole is the most prevalent site of MM. On the sole, however, melanocytic nevus is also frequently found. Clinical differentiation of early MM from benign melanocytic nevus on the sole is sometimes difficult because both are observed as a brownish-black macule. For the effective early detection of MM on the sole, the author has proposed guidelines based on the data of hundreds of melanocytic lesions on the sole. The algorithmic guidelines are as follows: when you see a pigmented lesion on the sole, first exclude congenital melanocytic nevus and some other specified disorders, and then measure the maximum diameter of the lesion. If it is more than 7 mm, biopsy it for histopathologic evaluation. If it is 7 mm or less, just follow the course of the lesion and advise the patient to come back if it enlarges to more than 7 mm. Even when the lesion is 7 mm or less, a biopsy is recommended on it, if it shows marked irregularity in shape and/or color or it shows the parallel ridge pattern with epiluminescence microscopy (ELM). The author believes the guidelines surely work efficiently in screening early MM on the sole.