Rice H E, Flake A W, Hori T, Galy A, Verhoogen R H
Department of Surgery, University of California, San Francisco.
J Pediatr Surg. 1994 Dec;29(12):1561-4. doi: 10.1016/0022-3468(94)90216-x.
Thymic hyperplasia is a rare cause of an anterior mediastinal mass in children. True thymic hyperplasia is characterized by massive thymic hypertrophy with retention of normal thymic architecture, and must be distinguished from more commonly seen tumors of the anterior mediastinum. Previous reports of thymic hyperplasia primarily have been descriptive, with minimal analysis of the cellular characteristics of the tumor. To better describe the cellular characteristics of thymic hyperplasia, the authors report on a 10-year-old boy found to have an asymptomatic left paracardiac mass during cardiac evaluation. The mass enlarged rapidly during the following 2 weeks and filled the entire left side of the chest. An open biopsy specimen showed normal thymic architecture. Because of the size and rapid growth of the mass, the authors decided to resect it. Cellular analysis of the mass did not show differences from normal thymic elements. There was conserved thymic architecture. The expression of cell surface markers and the proliferative response of thymocytes to cytokines appeared to be normal. Similarly, a long-term cell culture of the thymocytes did not result in clonal proliferation. Immunohistologic staining of stromal cells showed no striking differences from normal thymic elements. Moreover, immunologic analysis of the patient by standard hematological parameters, lymphocyte subsets, quantitative immunoglobins, and immunoelectrophoresis showed no abnormalities except for lymphocytosis, which resolved after tumor resection. The authors conclude that thymic hyperplasia occurs in immunologically normal children and may exhibit (1) rapid growth with minimal associated symptoms, (2) normal thymic architecture, (3) normal thymocyte and stromal growth characteristics in vitro, and (4) a normal thymocyte response to cytokine stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)
胸腺增生是儿童前纵隔肿块的罕见病因。真性胸腺增生的特征是胸腺大量肥大且保留正常胸腺结构，必须与更常见的前纵隔肿瘤相鉴别。以往关于胸腺增生的报道主要是描述性的，对肿瘤细胞特征的分析极少。为了更好地描述胸腺增生的细胞特征，作者报告了一名10岁男孩，在心脏评估期间发现有无症状的心旁左侧肿块。在接下来的2周内肿块迅速增大，占据了整个左侧胸腔。开放活检标本显示胸腺结构正常。由于肿块的大小和快速生长，作者决定将其切除。肿块的细胞分析未显示与正常胸腺成分有差异。胸腺结构得以保留。胸腺细胞表面标志物的表达以及胸腺细胞对细胞因子的增殖反应似乎正常。同样，胸腺细胞的长期细胞培养未导致克隆性增殖。基质细胞的免疫组织化学染色与正常胸腺成分无明显差异。此外，通过标准血液学参数、淋巴细胞亚群、定量免疫球蛋白和免疫电泳对该患者进行的免疫学分析除淋巴细胞增多外无异常，淋巴细胞增多在肿瘤切除后消失。作者得出结论，胸腺增生发生在免疫功能正常的儿童中，可能表现为：（1）生长迅速且相关症状轻微；（2）胸腺结构正常；（3）体外胸腺细胞和基质生长特征正常；（4）胸腺细胞对细胞因子刺激反应正常。（摘要截选至250词）
