Dermoscopy: An aid to the detection of amelanotic cutaneous melanoma metastases

Background: The recognition of amelanotic cutaneous melanoma metastases (ACMM) remains a diagnostic challenge. Objectives: To describe and analyze the clinical and dermoscopic characteristics of ACMM. Patients and Methods: Cases of ACMM were retrospectively selected from the image databases of three dermatology centers. The clinical and dermoscopic images were combined into one database for analysis. Results: Forty-seven ACMM were observed in 18 patients. All lesions were erythematous, symmetric, dome-shaped papules or nodules appearing an average of 17 months after the diagnosis of the primary melanoma. ACMM presented as clinical outliers or as nonspecific papules found by palpation of the skin. The predominant dermoscopic feature was the presence of vascular structures, including serpentine (45%), glomerular (30%), irregular hairpin (23%) and corkscres-like vessels (19%). A few lesions also revealed crystalline (or shiny white lines) when viewed using polarized dermoscopy. Conclusion ACMM should be considered in the differential diagnosis of new or persistent skin-colored or pink papules in patients with a previous history of invasive melanoma, especially if the lesions reveal atypical vessels under dermoscopy. The presence of crystalline structures may be another clue for the detection of some ACMM.