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.

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.