Amelanotic and hypomelanotic melanoma (AHM) have a higher risk of delayed diagnosis and significantly lower 5‐year melanoma‐specific survival than pigmented melanoma. The researchers aimed to evaluate the clinicopathological/dermoscopic features of amelanotic melanoma (AM) and hypomelanotic melanoma (HM). All participants had a personal history of AHM. They defined HM as showing clinical/dermoscopic pigmentation in < 25% of the lesion’s surface and histopathological focal pigmentation, while AM as melanomas with clinical/dermoscopic and histopathological absence of pigmentation.

The most common phenotypic traits among the 145 AHM patients were phototype II, blue‐grey eyes, and dark brown hair. Red hair was present in 23.8% of AHM cases. The most affected area was the back. A total of 67.1% were classified as AM and 32.9% as HM. The most represented hair colors in AM and HM were, respectively, blonde and dark brown hair. Median Breslow thickness was 1.7 mm, superficial spreading melanoma (SSM) and nodular melanoma (NM) were the most represented histotypes, and mitotic rate > 1 × mm2 was reported in cases. Regression was significantly more present in HM. Dermoscopy showed a high prevalence of white structureless zones, linear looped vessels, linear irregular vessels, and arborizing vessels. Multivariate logistic regression confirmed the association between pigmentation and the following: histological regression, dermoscopic globules, and arborizing vessels.

Ref: https://onlinelibrary.wiley.com/doi/10.1111/ijd.15064