Foot Melanoma Localized to Subungual Toe Location Portends Poorer Prognosis

Our group previously reported that melanoma of the foot is associated with advanced disease on diagnosis and decreased survival. Lesions localized to the toe appeared to have the worst outcomes. In this study, we both expanded our study to include a 10-year population of patient with invasive melanoma of the foot and ankle and investigated additional factors associated with prognosis. Between January 2007 and December 2016, 211 patients underwent biopsy diagnosis and surgery for invasive melanoma in the BLANK health care system. Demographic, pathologic, staging, and localization characteristics were studied for overall survival. Lesions were localized to dorsal foot, plantar foot, toe (nonsubungual), and toe (subungual) locations. Multivariable analysis found Breslow depth, ulceration, lymph node involvement, and subungual toe location to be associated with poorer survival. Overall survival rate for foot melanoma was 70.6%. Overall survival for nonsubungual toe melanoma was 60.7%, compared to 53.1% for subungual toe melanoma. Of the subungual melanomas, 37.5% of presented as deep lesions with a Breslow depth >4.0 mm. Subungual melanoma was statistically significant for and found to be an independent prognostic factor associated with poorer survival and advanced disease. Based on the results of this study, there should be a low threshold to biopsy suspicious lesions of the toe and foot with particular attention to be dedicated to subungual lesions.