蓝痣（BN）是一种良性皮肤黑素细胞增生的广泛类型，与普通痣和Spitz痣的遗传特征不同，常发生于Gαq基因的热点突变区域。在临床上，BN表现出女性优势、特定的发病部位和与皮肤特定区域的早期胚胎遗传事件相关的多种亚型。在组织学上，大多数BN位于真皮层，并伴有小型、灰白色、富有分支的色素瘤细胞，位于纤维素底层。肿瘤体积、纤维化和黑色素染色质量可能会有不同。肿瘤细胞数量和大小的增加可以在一些肿瘤中发生，因此它们获取细胞蓝痣的形态特征，具有二相性结构，表面呈现富有分支的蓝色痣组织形态，深部垂直生长的细胞扩张部分通常可达皮下组织。硬化和粘液性变体可以单独或组合出现，这将给病理诊断带来复杂性。细胞性蓝痣的恶性转化是罕见的，中间阶段被称为非典型细胞性蓝痣。恶性蓝色黑色素瘤是一个快速生长、体积较大、有明显恶性特征的黑色肿瘤。然而，它们很难与其他恶性皮肤黑素细胞增生鉴别。在这里，我们将详细介绍和阐述蓝痣及相关实体在皮肤中的广泛谱系的临床、组织学和遗传特征。版权所有© 2022年澳大利亚皇家病理学学院。由Elsevier B.V.出版。保留所有权利。

Blue naevi (BN) form a wide group of benign dermal melanocytic proliferations. They are genetically distinct from common and Spitz naevi with frequent hotspot mutations occurring in Gαq genes. Clinically, BN display a female predominance, elective sites of emergence and a great variety of subtypes related to specific regions of the skin linked to early embryological genetic events. Histologically, most BN are located in the dermis with small, bland, spindled and dendritic pigmented melanocytes within a fibrous background. Variation in tumour volume, fibrosis, and melanin pigment load can be broad. A growth in size and cellularity can occur within a subset of tumours as they acquire the morphological features of cellular blue naevi, with a biphasic architecture associating a dendritic blue naevus morphology near the surface, and deep vertical cellular expansions of medium-sized, bland melanocytes often reaching the subcutis. Sclerosing and myxoid variants can be observed either as individual or combined modifications that can add complexity to an otherwise straightforward diagnosis. Malignant progression of a cellular blue naevus is exceptional with an intermediate stage named atypical cellular blue naevus. Malignant blue melanomas are fast growing, large, pigmented tumours with most often obvious features of malignancy. However, they are difficult to separate from other malignant dermal melanocytic proliferations. Herein, we will extensively detail and illustrate the clinical, histological and genetic features of the vast spectrum of blue naevi and related entities in the skin.Copyright © 2022 Royal College of Pathologists of Australasia. Published by Elsevier B.V. All rights reserved.