先天性痣伴增生性结节的临床病理分析

Proliferative nodules in congenital melanocytic nevi：a clinicopathological analysis of eight cases

目的：探讨先天性痣伴增生性结节的临床病理特点、鉴别诊断及预后。方法收集2005年至2012年8例先天性痣伴增生性结节，总结其临床病理、治疗和随访资料。常规HE和免疫组织化学EnVision法染色行组织病理形态学观察。结果患者年龄1～54岁（平均27.6岁），发生部位分别为面部3例、背部2例、上肢2例、下肢1例。组织学上，8例均于先天性痣背景中见到膨胀性生长的黑色素细胞增生性结节，结节内细胞显示不同程度的多型性，核分裂象（0～4）个/10 HPF不等，其中6例增生性结节内黑色素细胞与结节周围先天性痣细胞有局部过渡现象。根据组成增生性结节的黑色素细胞组织学形态不同，分为卵圆形大细胞型（4例）、小细胞型（2例）和Spitz 痣样型（2例）。增生性结节中的黑色素细胞与其周边先天性痣细胞的免疫表型一致，均弥漫表达S-100蛋白，但不表达或仅散在表达HMB45。8例增生性结节Ki-67阳性指数均＜5％。随访时间9～82个月（中位时间54.5个月），7例行单发结节切除者均无复发，1例多发性结节者随访62个月后结节无显著变化。结论增生性结节是一种伴发于先天性痣的罕见的黑色素细胞增生性病变。充分认识其组织病理形态可以避免误诊为恶性黑色素瘤。此类病变特别是伴有不典型性组织学特征的增生性结节患者的预后有待于长期密切随访。

Objective To study the clinicopathologic features , differential diagnosis and prognosis of proliferative nodules （ PNs） in congenital melanocytic nevi （ CMN）.Methods Histopathologic evaluation and immunohistochemical study by EnVision method were carried out in 8 cases of PNs in CMN.The clinical information and follow-up data were analyzed.Results The age of patients ranged from 1 to 54 years （ mean 27.6 years）.Tumors were located on face （3 cases）, on back （2 cases）, upper extremities （2 cases） and lower extremities（1 case）.Microscopically, PNs with expansile growth were observed in 8 cases of CMN.Melanocytes in PNs show variable pleomorphism with a mitotic activity of 0 to 4 per 10 high power fields.Blending of cells with adjacent CMN was noted in 6 cases.According to the morphology of melanocytes in PNs, it was classified into different types including large oval melanocytes （ 4 cases ） , small melanocytes （2 cases） and Spitz-nevus-like forms （ 2 cases ）.Immunohistochemically , melanocytes in PNs were consistent with those in adjacent CMN.They were diffusely positive for S-100 protein, but were either negative or focally positive for HMB45.Less than 5% of melanocytes were positive for Ki-67 in 8 cases of PN.Follow-up was available in all cases , ranging from 9 to 82 months.Seven patients with excision of single PN in CMN were alive with no evidence of disease , while 1 patient with multiple PNs in CMN was stable with disease after 62 months follow-up.Conclusions PN is a rare melanocytic lesion arising in CMN.Recognition of its specific histologic features can help to avoid being misdiagnosed as melanoma .Long term follow-up should be recommended in patients with PNs , especially in those with atypical histologic features.Further investigation is needed to elucidate its clinical behavior.