Zúñiga-Castillo M, et al. - Authors sought to compare the density of M2-Ms in acral lentiginous melanoma (ALM) vs superficial spreading melanoma (SSM), and to analyze regardless of whether the density of M2-Ms is correlated with histopathological features predictive of adverse prognosis in cutaneous melanoma (CM), as well as development of metastasis. They analysed sixty-seven ALMs and 67 SSMs cases. In this first investigation addressing this topic, the increased presence of M2-Ms in ALM than SSM was found. They reported that the increased M2-Ms in ALM were linked with the main histopathological features predictive of adverse prognosis in CM, and additionally the presence of metastasis and that these cells can be related to the aggressive behaviour observed in ALMs.