BACKGROUND Melanoma in situ (MIS) diagnosed from a subtotal biopsy may be upstaged to invasive melanoma after resection. The frequency of this phenomenon is markedly variable. OBJECTIVE To quantify the rate of upstaging MIS on the head and neck after resection at this institution, characterize the location of the invasive component relative to the clinically evident lesion, and determine the rate of upstaging with time. MATERIALS AND METHODS The authors retrospectively reviewed clinical records of adult patients with a preoperative diagnosis of MIS on the head and neck from January 1994 to August 2012. Patient and tumor characteristics were recorded. RESULTS In total, 624 patients met the inclusion criteria and 24 (4%) were upstaged after resection. Four patients had invasive disease beyond the clinically evident lesion. The annual percentage of upstaged lesions seemed to show an increasing trend with time. CONCLUSION Upstaging of MIS on the head and neck occurs at a relatively low rate that may be increasing with time. Invasive components of lentigomaligna melanoma may exist beyond the clinically evident margins. Histological examination of the maximal amount of the surgical specimen is paramount for optimal staging and treatment of MIS.
ASJC Scopus subject areas