Department of Anatomical Pathology, PathWest Laboratory Medicine, QEII Medical Centre, Perth, WA, Australia.
School of Pathology and Laboratory Medicine, University of Western Australia, Perth, WA, Australia.
Am J Dermatopathol. 2021 Mar 1;43(3):182-190. doi: 10.1097/DAD.0000000000001721.
The distinction between nevoid melanoma and a mitotically active nevus can be challenging at the microscopic level. In this study, we performed cytogenetic testing on a cohort of 25 mitotically active melanocytic proliferations resembling common melanocytic nevus from 25 patients. Based on cytogenetic findings, the lesions were classified as "nevoid melanoma" (n = 13) or "mitotically active nevus" (n = 12). Subsequently, we compared the clinicopathological features between these 2 groups. Nevoid melanomas occurred in older patients (P = 0.007); however, there were no significant differences in gender, size, or anatomical distribution between the 2 groups. Histologically, deep/marginal mitoses (P = 0.006), lack of maturation with depth (P = 0.036), and pseudo-maturation (P = 0.006) were significantly more common in nevoid melanomas. Immunohistochemically, complete loss of p16 was an important divisive feature (P = 0.0004), seen in 70% of nevoid melanomas, and highly correlated with loss of CDKN2A gene (chromosome 9p21). Our findings suggest that such reproducible immunomorphological differences can be of value in distinguishing nevoid melanoma from mitotically active nevus. Nevoid melanomas demonstrated a spectrum of chromosomal aberrations similar to those seen in common subtypes of melanoma, which can serve as a powerful adjunct diagnostic tool in morphologically challenging lesions.
在显微镜下，区分痣样黑素瘤和有丝分裂活性痣可能具有挑战性。在这项研究中，我们对 25 例来自 25 名患者的具有有丝分裂活性的类似于常见黑素细胞痣的黑素细胞增生进行了细胞遗传学检测。根据细胞遗传学发现，这些病变被分类为“痣样黑素瘤”（n = 13）或“有丝分裂活性痣”（n = 12）。随后，我们比较了这两组之间的临床病理特征。痣样黑素瘤发生在年龄较大的患者中（P = 0.007）；然而，两组之间在性别、大小或解剖分布方面没有显著差异。组织学上，深层/边缘有丝分裂（P = 0.006）、缺乏深度成熟（P = 0.036）和假性成熟（P = 0.006）在痣样黑素瘤中更为常见。免疫组织化学上，p16 完全缺失是一个重要的区分特征（P = 0.0004），见于 70%的痣样黑素瘤，与 CDKN2A 基因（9p21 号染色体）缺失高度相关。我们的研究结果表明，这种可重复的免疫形态学差异对于区分痣样黑素瘤和有丝分裂活性痣具有重要价值。痣样黑素瘤表现出与常见黑色素瘤亚型相似的染色体异常谱，可作为形态学具有挑战性病变的有力辅助诊断工具。
