Dermoscopic features of amelanotic cutaneous melanoma metastases: evidence from four cases

Cutaneous metastases of malignant melanoma (MM) are relatively common, occurring in 2-20% of cases. These metastases typically present as pigmented papules or nodules but can occasionally manifest in unusual forms, such as amelanotic cutaneous melanoma metastases (ACMMs). Due to their relative rarity (less than one-third of cutaneous metastases of MM), definitive dermoscopic characterization of ACMMs remains elusive. This case series investigates the dermoscopic features of four ACMM cases, all of which exhibited vascular patterns. Consolidating our findings with existing literature, polymorphic vessels and linear irregular/serpentine vessels emerge as the predominant patterns in ACMMs. Notably, in one case, the primary melanoma was initially unrecognized, with metastases appearing as the initial manifestation of the disease. This series underscores the need to establish precise dermoscopic criteria for ACMMs.