结缔组织增生性色素痣四例临床病理分析

Clinicopathologic analysis of four cases of desmoplastic melanocytic nevus

目的探讨结缔组织增生性色素痣的病理学特点及鉴别诊断。方法对4例皮肤结缔组织增生性色素痣的临床表现、组织学表现、免疫组化及荧光原位杂交（FISH）特点进行分析。结果4例结缔组织增生性色素痣中，男2例，女2例，年龄19～30岁，平均26．5岁；皮损位于四肢3例，外阴1例。组织学特点：均为皮内痣，病变左右对称，痣细胞呈上皮样和（或）梭形，聚集成团或单个散在分布于增生的纤维组织之间，均未见淋巴细胞聚集、坏死或溃疡。免疫组化显示，3例痣细胞为S100和MelanA阳性，2例为P16阳性；Ki-67阳性指数均小于5％；2例间质细胞为凝血因子F）皿和CD34阴性。荧光原位杂交（FISH）显示结缔组织增生性色素痣在6p25（RREBl）、6q23（MYB）、6p11.1-q11．1（Cep6）及11q13（CCND1）4个基因位点均无拷贝数异常。结论结缔组织增生性色素痣是一种组织学独特的良性黑素细胞痣，ki-67、S100、Melan A、凝血因子FⅫ等免疫组化染色和黑素瘤FISH检测有助于其与皮肤纤维组织细胞瘤和黑素瘤鉴别。

Objective To investigate pathological characteristics and differential diagnosis of desmoplastic melanocytic nevus. Methods Four cases of desmoplastic melanocytic nevus were analyzed based on the clinical manifestations and histological, immunohistochemical and fluorescence in situ hybridization （FISH） features. Results Of the 4 cases, 2 were male and 2 were female. Their age ranged from 19 to 30 years with the average age being 26.5 years. The skin lesions were located on the extremities in 3 cases, on the vulva in 1 case. Histologically, the lesions were bilaterally symmetrical intradermal nevus. Nevus cells appeared epithelioid and/or fusiform, some were clustered or scattered in the proliferative fibrous tissue. None of lymphocyte aggregation, necrosis or ulceration was observed. Immunohistochemical examination showed positive staining for S100 and Melan A in 3 cases, positive staining for P16 in 2 cases, Ki-67-1abeling index less than 5% in all the 4 cases, and negative staining for factor XIII （FXIII） and CD34 in 2 cases. FISH assay showed no copy-number variations in gene loci 6p25 （RREB1）, 6@3 （MYB）, 6p11.1-q11.1 （Cep6） and 11q13 （CCND1） in desmoplastic melanocytic nevus. Conclusion Desmoplastic melanocytic nevus is a kind of histologically unique, benign melanocytic nevus, and immunohistochemical staining for Ki-67, S-100, Melan A and F Ⅻ and FISH assay on melanoma can be helpful for the differential diagnosis between cutaneous fibrous histiocytoma and melanoma.