[Clinicopathological features and prognosis of ALK-positive Spitz tumors].

Objective: To investigate the clinicopathologic features and prognosis of ALK-positive Spitz tumors. Methods: Thirteen patients with ALK-positive Spitz tumors diagnosed at Shanghai Cancer Center, Fudan University from October 2016 to December 2017 were collected. All cases were routinely evaluated histopathological features in HE staining and detected ALK protein expression by immunohistochemistry. The ALK fusions of 7 cases were confirmed by fluorescence in situ hybridization (FISH).Follow-up data was collected. Results: The age of patients including 2 males and 11 females ranged from 4 to 47 years (mean 25 years). 12 patients were diagnosed with atypical Spitz tumors and 1 patient was diagnosed with Spitz nevus. Clinically, most lesions presented as papules or nodules, while a few lesions presented as plaques. Histologically, most tumors were exophytic (9/13). More than half of the tumors were amelanotic and the junctional component was mainly composed of melanocytic nests. Kamino bodies were not found. The bases of the tumors were mainly wedge-shaped (5/13) and flat (7/13). Eight tumors displayed mixed cell types, while 5 tumors were composed of only spindle cells. All the tumors showed a plexiform and/or intersecting fascicular growth pattern, and perineural extension was observed in 3 tumors. ALK immunohistochemistry showed diffuse and intense cytoplasmic staining in 13 cases, and 7 of them were detected by FISH to confirm the presence of ALK fusions. All patients were followed up for 7 to 21 months (median=12), with no recurrence or lymph node dissemination. Conclusions: Spitz tumors with ALK fusions have their special histopathologic features.ALK fusions mainly occur in Spitz nevi and atypical Spitz tumors. The follow-up data of the existing literatures and our research indicates that the prognosis of ALK-positive Spitz tumors may be good.目的： 探讨间变性淋巴瘤激酶（ALK）阳性的Spitz肿瘤临床病理学特征及预后。 方法： 收集2016年10月至2017年12月间复旦大学附属肿瘤医院诊断的ALK阳性Spitz肿瘤病例13例，常规行HE染色和免疫组织化学染色检测ALK蛋白表达，对7例行荧光原位杂交（FISH）检测ALK相关融合基因，并进行随访。 结果： 患者男性2例，女性11例，年龄4~47岁（平均年龄25岁）。12例诊断为不典型Spitz肿瘤，1例诊断为Spitz痣。临床上，多数患者表现为丘疹或结节，少数为扁平斑块。组织学上，大多数病变以外生型构型为主（9/13），半数以上病例无明显黑色素沉着，表皮内交界成分以黑色素细胞巢团状分布为主，未见Kamino小体。肿瘤基底部构型主要以楔形（5/13）及平坦形为主（7/13）。肿瘤细胞形态为上皮样细胞与梭形细胞混合型8例，单一梭形细胞形态5例，所有病变细胞均呈丛状和/或交叉束状生长模式，3例存在小神经包绕。13例ALK免疫组织化学检测均示肿瘤细胞胞质弥漫强阳性，其中7例行FISH检测证实存在ALK融合基因。所有患者均获随访，随访时间7~21个月（中位数为12个月），均未出现局部复发或淋巴结播散。 结论： 伴有ALK融合基因的Spitz肿瘤具有其特殊的组织病理学特征，主要发生于Spitz痣及不典型Spitz肿瘤中，其临床生物学行为可能较好。.