Tumour-Vascular Interface in melanomas with Breslow thickness ≥0.8 mm: A Confocal Microscopy Study

Background Due to the limited laser penetration depth, reflectance confocal microscopy (RCM) application in the study of thick cutaneous lesions has been limited so far. Objectives To describe clinical, histopathological, dermoscopic and RCM features of cutaneous melanomas with Breslow thickness ≥0.8 mm, to identify possible differences among different histological subtypes, and describe new RCM features of these tumours, with a focus on their potential impact on prognosis. Methods We conducted a retrospective, single-centre, study. We assessed the presence of a new RCM feature named “tumour-vascular interface” (TVI) defined as the presence of vessels adjacent to melanocytic structures. The included cases were classified according to melanoma histotype and the presence of TVI. Results A total of 197 melanomas were included and comprehensive description of their clinicopathological, dermoscopic and RCM features was provided. Most cases were superficial spreading melanomas (72.6%) and nodular melanomas (16.2%). The mean Breslow thickness was 2.3 mm (SD ±2.4; range 0.8-25). TVI was identified in 83 cases (42.1%). TVI+ cases were more frequently amelanotic/hypomelanotic (p = 0.011) and ulcerated (p= 0.093) and exhibited a higher mitotic rate (p=0.002). No significant differences in mortality rate or disease progression were observed between TVI+ and TVI- melanomas though TVI+ cases showed a trend toward higher nodal relapse rates (p=0.068). Conclusions This study provides an in-depth analysis of clinicopathological, dermoscopic and RCM features of invasive cutaneous melanomas, suggesting a potential new application of RCM in the study of melanoma vascularization and its possible correlation with clinical behaviour