The hunt for baby melanomas: a prospective study of the dermoscopy features on 100 small melanoma cases with in vivo surface diameters up to a maximum of 6mm.

Abstract

Background:: Early diagnosis can improve melanoma prognosis. Dermoscopy can enhance early melanoma recognition. Objectives: Examine the dermoscopy features of early melanoma up to a maximum surface diameter of 6mm. Methods: Consecutive melanoma cases were collected from two medical practices in Sydney, Australia 2019-2021. Dermoscopy features were recorded for melanomas by maximum surface diameter, to the nearest 0.1 mm, to a limit of 6mm. Results: Total cases numbered 100; with males (n=48) and females (n=52), melanoma in situ (MIS, n=96) and invasive (n=4). The most frequent anatomic sites on both males and females were back (males n=20, females n=16) then knee or leg (males n=8, females n=12). Minimum respective MIS diameters for males/females was 1.2/2.0mm and for invasive cases 2.0/3.4mm. Highest frequency dermoscopy features were: light brown, dark brown, grey and asymmetric melanoma shape. Brown pigment in hair follicles were more frequent on legs compared to other anatomic sites [OR 14.6, 95%CI (1.29-165.17), p 0.03]. Pseudopods were substantially increased in frequency comparing diameters less than 4mm with 4 up to 6mm [OR 8.81, 95%CI (1.05-73.9), p 0.004]. Structureless area cases recorded increased grey [OR 7.08, 95%CI (1.61-31.11) p=0.01]. Melanomas with edge angulation were noted in 20-50% of cases across diameters 1-6mm, less frequent were pigmented circles and polygons. Conclusion: Watch out! MIS presented with a surface diameter of just 1.2 mm and invasive melanoma 2.5mm. Pseudopods were a strong clue to melanomas with a surface diameter less than 5mm. We found melanomas on leg sites displayed more frequent pigmented hair follicles.

Keywords

• early small melanoma, dermoscopy, confocal microscopy, pigmented hair follicles, pseudopods, polygons.