Clinicopathological and dermoscopic features of amelanotic and hypomelanotic melanoma: a retrospective multicentric study

Abstract

Background Amelanotic and hypomelanotic melanoma (AHM) has a higher risk of delayed diagnosis and a significant lower 5-year melanoma-specific survival compared to pigmented melanoma. Our aim was the evaluation of the clinicopathological/dermoscopic features of amelanotic melanoma (AM) and hypomelanotic melanoma (HM). Methods All participants had a personal history of AHM. We 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. Results The most common phenotypic traits among the 145 AHM patients were as follows: phototype II, blue-grey eyes, and dark brown hair. Red hair was present in 23.8% AHM cases (AM = 22.60%; HM = 25.80%). The most affected area was the back (29.5%). 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 9 mm 2 was reported in 73.3% cases, and regression was significantly more present in HM. Dermoscopy showed high prevalence of white structureless zones (63.4%), linear looped vessels (58.8%), linear irregular vessels (50.0%), and arborizing vessels (47.2%). Multivariate logistic regression confirmed the association between the presence of pigmentation and the following: histological regression, dermoscopic globules, and arborizing vessels. Conclusions Predominance of red hair in AHM patients was not confirmed. AHM affects mostly intermittent sun-exposed body areas. The deeper median Breslow thickness (versus pigmented melanoma), the association of AM with the nodular histotype, and the high mitotic rate highlight the AHM's aggressiveness. HM's higher levels of regression can be explained by the presence of pigmentation, driving the underlying immune response. AHM showed a polymorphous vascular pattern and significant presence of arborizing vessels (especially HM).

Dermoscopic Features of Amelanotic and Hypomelanotic Melanomas: A Review of 49 Cases

“…Dotted vessels were present in nearly half of our cases. This was similar to the incident reported in the literature [1]). Zalaudeket al reported a strong association between dotted and AHM with Breslow thickness less than 1 mm [4].…”

“…Short white lines were most common finding in our cohort, seen in 79.6% of cases. This is higher than reported observations at 30.8% [1]. We assume reviewing magnified images on the monitor contributed to better visualization of these subtle features.…”

Targeting Melanoma-Initiating Cells by Caffeine: In Silico and In Vitro Approaches

“…In fact, the detection of TYR mRNA in peripheral blood relates to the occurrence of melanoma metastases [49]. Nevertheless, amelanotic melanomas show more aggressive features (due also to a higher probability of misdiagnosis) and have a poorer survival rate [50]. This observation is in line with our in silico analyses, which emphasize how low TYR levels are associated with poor clinical outcome.…”

Acral Amelanotic Melanoma Mimicking a Foot Ulcer

“…While amelanotic melanoma is a universal clinical diagnostic challenge, dermoscopy can be helpful, potentially revealing features such as white structureless zones, milky-red areas, or arborizing, linear looped, or linear irregular vessels, indicating an increased likelihood of amelanotic melanoma [9]. However, it is not perfect, as amelanotic acral melanoma may be dermoscopically featureless [2].…”