Department of Dermatology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
Am J Surg Pathol. 2013 Jan;37(1):81-8. doi: 10.1097/PAS.0b013e3182608fa5.
Epithelioid blue nevus (EBN) was first described in patients with Carney complex (CNC) and subsequently shown to also occur sporadically. Over 50% of patients with CNC harbor mutations in the gene PRKAR1A, which codes for protein kinase A regulatory subunit 1α (R1α) involved in the signaling pathway regulating melanogenesis and melanocytic proliferation. Immunohistochemical expression of R1α has been shown to be absent in the majority of pigmented epithelioid melanocytomas and all CNC-associated EBNs but present in melanomas and other melanocytic nevi. We have observed several examples of EBN occurring in chronically sun-damaged (CSD) skin with a predominance of epithelioid morphology but also containing a component of fusiform and conventional blue nevus cells, which we have termed epithelioid and fusiform blue nevus of CSD skin. Several of these cases demonstrated notable pleomorphism and nuclear atypia with rare mitotic activity raising concern for the possibility of melanoma; however, the clinical outcomes, detailed histologic review, and molecular results were most consistent with a benign melanocytic neoplasm. We report our clinical, histopathologic, immunohistochemistry, and fluorescence in situ hybridization experience with this distinct entity of epithelioid and fusiform blue nevus and demonstrate that it is a unique subtype of blue nevus occurring on CSD skin with a higher frequency of an associated conventional blue nevus component compared with EBN and without association with CNC or loss of R1α expression typically found in pigmented epithelioid melanocytoma and CNC-associated EBN. We also postulate that the epithelioid pattern may represent a subclone of the conventional blue nevus component induced by chronic UV damage.
上皮样蓝痣（EBN）最初在卡尼综合征（CNC）患者中被描述，随后也被发现散发性发生。超过 50%的 CNC 患者携带 PRKAR1A 基因突变，该基因编码蛋白激酶 A 调节亚单位 1α（R1α），参与调节黑色素生成和黑素细胞增殖的信号通路。免疫组化 R1α 的表达在大多数色素性上皮样黑素细胞瘤和所有 CNC 相关的 EBN 中均缺失，但在黑色素瘤和其他黑素细胞痣中存在。我们观察到几个 EBN 发生在慢性日光损伤（CSD）皮肤中的例子，以上皮样形态为主，但也包含梭形和传统蓝痣细胞的成分，我们将其命名为 CSD 皮肤的上皮样和梭形蓝痣。这些病例中的几个表现出明显的多形性和核异型性，罕见有丝分裂活性，这引起了对黑色素瘤的可能性的关注；然而，临床结果、详细的组织学复习和分子结果最符合良性黑素细胞肿瘤。我们报告了我们在这种独特的上皮样和梭形蓝痣实体中的临床、组织病理学、免疫组织化学和荧光原位杂交经验，并证明它是 CSD 皮肤中发生的一种独特的蓝痣亚型，与 EBN 相比，其常规蓝痣成分的发生率更高，并且与 CNC 或通常在色素性上皮样黑素细胞瘤和 CNC 相关的 EBN 中发现的 R1α 表达缺失无关。我们还推测，上皮样模式可能代表由慢性 UV 损伤诱导的常规蓝痣成分的亚克隆。
