Quantitative evaluation of healthy epidermis by means of multiphoton microscopy and fluorescence lifetime imaging microscopy.

BACKGROUND/PURPOSE: Multiphoton microscopy (MPM) enables the assessment of unstained living biological tissue with submicron resolution, whereas fluorescence lifetime imaging microscopy (FLIM) generates image contrast between different states of tissue characterized by various fluorescence decay rates. The aim of this study was to compare the healthy skin of young individuals with that of older subjects, as well as to assess the skin at different body sites, by means of MPM and FLIM. METHODS: Nineteen elderly patients were examined on the outer side of the forearm, whereas 30 young individuals were assessed on the dorsal and volar sides of the forearm and on the thigh. RESULTS: Cell and nucleus diameters, cell density and FLIM vary according to the epidermal cell depth and the skin site. In elderly subjects, epidermal cells show morphologic alterations in shape and size, with smaller cell and nucleus diameters; the number of basal cells is decreased, whereas the mean fluorescence lifetimes at both the upper and the lower layers increase. CONCLUSION: This study provides quantitative and qualitative data on normal epidermis at different skin sites at different ages and represents a reference for the clinician attempting to understand the effectiveness of MPM and FLIM in discriminating diseased states of the skin from normal ones.

Dermoscopic island: a new descriptor for thin melanoma.

OBJECTIVES: To determine the frequency and the features of the dermoscopic island (DI) in melanocytic lesions and to assess its specificity for the diagnosis of melanoma. Dermoscopy improves the diagnostic accuracy of melanoma, but only a few dermoscopic descriptors specific for thin melanomas have been identified. We defined a new descriptor, the dermoscopic island, a well-circumscribed area showing a uniform dermoscopic pattern that differs from the rest of the pigmented lesion. DESIGN: Dermoscopic images of 96 in situ melanomas, 266 invasive melanomas, and 612 dermoscopic atypical nevi were evaluated to establish the presence and the main pattern of the DI. Also, clinical and histologic characteristics were analyzed. SETTING: Dermoscopic images were collected from lesions excised between 2003 and 2008 at the Department of Dermatology, University of Modena and Reggio Emilia. MAIN OUTCOME MEASURES: Specificity and odds ratio for melanoma; dermoscopic and histologic characteristics of lesions with a DI. RESULTS: The DI was present in 10.4% of in situ melanomas, 4.1% of invasive melanomas, and 3.1% of dermoscopic atypical nevi. The odds ratio for melanoma was 1.922, and specificity was 96.9%. Invasive melanomas with a DI were thinner than those lacking this descriptor. In addition, more than half of the melanomas with a DI arose on a nevus. The DI appeared mainly reticular on a reticular background. CONCLUSION: The DI is characteristic of thin melanoma arising in a nevus; thus, it can be considered a potential early sign of transformation of a nevus into a melanoma.