CRITICAL EFFECTS OF INTENSE SUN EXPOSURE ON THE EXPRESSION OF EPILUMINESCENCE MICROSCOPY FEATURES OF ACQUIRED MELANOCYTIC NEVI

Background: Current knowledge of the histologic counterparts of epilum inescence microscopy (ELM) features in pigmented skin lesions is limit ed. As a particular aspect of this problem, the transient effects of i ntense sun exposure on the morphological characteristics of melanocyti c nevi may influence the expression of ELM features as well as the dem onstration of stable and consistent histologic correlates. Observation s: Forty melanocytic nevi from 11 subjects living in Northern Italy we re examined by digital ELM before and after 5 to 13 days of sun exposu re at latitudes of 5 degrees north to 3 degrees south. A number of mul tifaceted changes were observed. In particular, 3 lesions showed the e xpression of some structures compatible with radial streaming, pseudop ods, and gray-blue areas. These features are considered to have often severe histologic correlates. In a third image, obtained 5 to 6 weeks later, they showed partial or total regression. Another case showed a massive regression of the pigment network as a result of a progressive inflammatory reaction with marked asymmetry in the distribution of pi gmentation. Conclusions. Digital ELM has the potential to detect subtl e changes in the structure of nevi after intense sun exposure. The tra nsient observation of certain ELM features often associated with sever e histologic substrates casts doubts on the ability of ELM to characte rize sun-exposed nevi by a single examination.