Melanocytic soluble adenylyl cyclase protein expression around lentigo maligna and in contralateral control skin

Recurrence rates of both lentigo maligna (LM) and lentigo maligna melanoma (LMM) following conventional surgery are usually relatively high. We aimed to assess the frequencies of melanocytes in tumour-free margins around LM/LMM using soluble adenylyl cyclase (sAC) immunohistochemistry, and to compare these with those of matched healthy contralateral skin. Using the primary mouse-anti-human sAC antibody R21, we evaluated pan-nuclear melanocytic R21 immunostaining, and found that it was significantly (P < 0.001) higher in peritumoural melanocytes (median 20%; range 0-100%) than in contralateral healthy skin (mean 0%; range 0-20%). Accordingly, there was no correlation between peritumoural and contralateral R21 immunoreactivity (r = 0.12; P = 0.18). In conclusion, melanocytic R21 immunoreactivity in melanocytes is higher in tumour-free margins around LM/LMM than in site-matched contralateral skin. This observation may indicate that the biology of 'healthy'-appearing melanocytes around LM/LMM might be different from that of truly benign melanocytes.