NRAS Q61 突变是与常见黑素细胞痣相关的驱动基因改变。在此，我们描述了一例具有蓝色痣样形态的 NRAS 突变黑素细胞肿瘤。一名 71 岁的日本男子背部出现 4.6 毫米的结节。组织病理学检查显示，真皮上层有密集分布的纺锤形黑素细胞，真皮中层有稀疏分布的树突状黑素细胞。垂直的附件周围延伸到达肿瘤中心的深层真皮。观察到小的连接成分、色素沉着过度、硬化基质、轻度核异型性和一些有丝分裂像。免疫组织化学检查显示没有 PRAME 表达，但保留了 p16 表达。在这些肿瘤细胞中观察到弥漫性 RASQ61R 免疫反应性。未观察到核β-连环蛋白表达。靶向 RNA 测序显示两种突变：NRAS c.182A>G (Q61R) 和 FGFR2 c.-157A>G，但没有其他致病性改变，例如 BRAF、GNAQ、GNA11、CTNNB1、PRKAR1A 或 IDH1 突变或激酶基因融合。组织病理学符合复合型蓝痣，称为“卡米诺痣”；然而，这种肿瘤在基因上被认为属于传统获得性黑素细胞痣的范围，而不属于蓝痣的范围。从形态上看，NRAS 驱动的黑素细胞痣类似于没有 IDH1R132C 共存的蓝痣。© 2024 John Wiley

NRAS Q61 mutations are driver genetic alterations associated with common melanocytic nevi. Herein, we describe a case of NRAS-mutant melanocytic tumor with a blue nevus-like morphology. A 71-year-old Japanese man presented with a 4.6-mm nodule on his back. Histopathological examination revealed a dense distribution of spindle-shaped melanocytes in the upper dermis and a sparse distribution of dendritic melanocytes in the mid-dermis. The vertical periadnexal extension reached the deep dermis at the center of the tumor. A small junctional component, hyperpigmentation, sclerotic stroma, mild nuclear atypia, and a few mitotic figures were observed. Immunohistochemical examination revealed no PRAME expression and preserved p16 expression. Diffuse RASQ61R immunoreactivity was observed in these tumor cells. Nuclear β-catenin expression was not observed. Targeted RNA sequencing revealed two mutations, NRAS c.182A>G (Q61R) and FGFR2 c.-157A>G, but no other pathogenic alterations such as BRAF, GNAQ, GNA11, CTNNB1, PRKAR1A, or IDH1 mutations or kinase gene fusions. The histopathology fits that of compound-type blue nevus, which is called "Kamino nevus"; however, this tumor was genetically considered to be on the spectrum of conventional acquired melanocytic nevi but not on that of blue nevi. Morphologically, NRAS-driven melanocytic nevi resemble blue nevi without IDH1R132C coexistence.© 2024 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.