[Epithelioid hemangioendothelioma with TFE3 translocation in soft tissue:a clinicopathological study].

Objective: To investigate the clinicopathological and molecular features, diagnosis and differential diagnosis of TFE3-rearranged epithelioid hemangioendothelioma (EHE). Methods Two cases of TFE3-rearranged EHE arising from soft tissues, diagnosed by the Pathology Department of the First Affiliated Hospital of Nanjing Medical University from 2013 to 2020 were observed. EnVision method was used for immunophenotyping, fluorescence in situ hybridization (FISH) was used to test TFE3 gene rearrangements and WWTR1-CAMTA1 fusion gene,and next-generation sequencing (NGS) was used to delineate the fusion transcripts. Results: Details of these two cases were as follows: case 1, male, 51 years old, with tumor in the right temporal region; case 2, female, 42 years old, with tumor in the right neck. The tumors showed progressive painless enlargement. Grossly, the tumor of case 1 was multinodular with unclear boundary and grayish red cut surface, while the tumor of case 2, originating from a vein, appeared as a firm, tan mass within vessel wall. Microscopically, both tumors showed moderate cellularity and were consisted of plump, epithelioid, or histiocytoid cells with eosinophilic cytoplasm and mild-to-moderate nuclear pleomorphism. Most of the tumor cells were arranged in solid or alveolar growth patterns, while some tumor cells showed intraluminal papillary growth pattern in case 1 and anastomosing vascular channels and extramedullary hematopoiesis in case 2. Immunohistochemically, the tumor cells showed diffuse positivity for CD31, CD34, ERG, and TFE3. FISH revealed TFE3 break-apart signals in two cases, but WWTR1-CAMTA1 gene fusion was not detected. NGS identified YAP1 (exon1)-TFE3 (exon6) fusion gene in case 2. Clinical follow-up information was available in both cases for a follow-up period of 15 and 59 months respectively. Patient 1 had a relapse 22 months after surgery, and was currently alive with the tumor. Patient 2 remained disease-free. Conclusions: TFE3-rearranged EHE is a rare molecular subtype of EHE, with accompanying characteristic morphologic features. However the morphologic spectrum remains under-recognized, and more experience is needed. Immunohistochemical and molecular examinations are helpful for the diagnosis and differential diagnosis of the disease.目的： 探讨TFE3重排的上皮样血管内皮瘤（EHE）的临床病理学特征、分子特点、诊断及鉴别诊断。 方法： 收集2013—2020年南京医科大学第一附属医院病理科诊断的软组织TFE3重排的EHE共2例，采用EnVision法进行免疫组织化学染色，荧光原位杂交（FISH）法检测TFE3基因断裂重排及WWTR1-CAMAT1基因融合情况，二代测序检测其融合转录本。 结果： 患者2例，例1男，51岁，右颞部肿瘤；例2女，42岁，右颈部肿瘤。临床表现均为肿块无痛性进行性增大。大体检查，例1呈结节状生长，边界不清，切面灰红；例2在静脉壁内生长，切面淡褐色。镜下，2例均为中等细胞密度，胞质丰富嗜酸，似泡沫样或组织细胞样形态，核轻至中度多形性。大多数肿瘤细胞呈实性或腺泡状排列，但例1中观察到腔内乳头状生长方式，例2中观察到血管吻合沟通区域和髓外造血现象。免疫组织化学上，肿瘤细胞强阳性表达CD31（2/2）、CD34（2/2）、ERG（2/2）和TFE3（2/2）。FISH示TFE3基因断裂（2/2），未见WWTR1-CAMAT1基因融合（0/2）。二代测序示例2出现YAP1（exon1）-TFE3（exon6）融合。2例均获随访，随访时间15~59个月，例1术后22个月复发，目前带瘤生存，例2未复发。 结论： TFE3重排的EHE是一种少见的分子亚型，有特殊的形态学表现，但也可能有少见的形态学谱系；免疫组织化学及分子病理学辅助检查有助于疾病的诊断及鉴别诊断。.