Hunting for Early Melanomas With a Maximum Clinical Surface Diameter up to 6 mm: A Prospective Study of Reflectance Confocal Microscopy Features in 68 Consecutive Cases.

Abstract

Background: Early diagnosis of melanoma and prompt effective therapy optimizes prognosis. Reflectance confocal microscopy (RCM) facilitates diagnosis by providing immediate 3D single cell resolution down into the papillary dermis.

Methods: Consecutive cases were examined using a Vivascope 1500 confocal microscope at a single referral medical practice in Sydney, Australia 2019-2023. Melanoma clinical surface diameters were recorded by 0.1 mm increments up to 6.0 mm. The RCM features recorded were: pagetoid single cells or nests, pleomorphic cell shape, atypical dendritic cells, non-edged papillae, variation in melanocyte size and confluent sheets of cells. All cases required diagnostic agreement by two dermatohistopathologists using hematoxylin and eosin staining followed by SOX 10 and/or PRAME stains if required.

Results: Total cases were 68: 38 males (mean age 57) and 30 females (mean age 64). Melanoma in situ (n = 65) compared to invasive melanoma (n = 3), all males, invasion depth (0.4-0.5 mm). Most frequent RCM features found in 50% or more of cases within all diameter increments were: pagetoid single cells n = 64/68 (94%), pleomorphic cell shape n = 63/68 (93%), epidermal disarray n = 58/68 (85%), and atypical dendritic cells n = 45/68 (66%). Non-edged dermal papillae were n = 42/68 (62%).

Conclusion: Melanoma RCM features were found throughout the diameter ranges. Confocal examination may facilitate early melanoma recognition in these ranges.