Noh T W, Kim S H, Lim B J, Yang W I, Chung K Y
Department of Pathology, Yonsei University College of Medicine, C.P.O. Box 8044, Seoul 120-752, Korea.
Yonsei Med J. 2001 Oct;42(5):571-5. doi: 10.3349/ymj.2001.42.5.571.
Thymoma with psuedosarcomatous stroma is a recently described, rare variant of thymomas that are characterized by having a biphasic histologic pattern which consists of both an epithelial and a spindle cell stromal component. So far only 11 cases having similar histologic findings have been reported worldwide. At this time we report a case of this rare variant of thymoma which occurred in a 53-year-old Korean man. This previously healthy patient presented with coughing and an anterior mediastinal mass was then detected radiographically. Mediastinal exploration revealed a 9 x 8 x 8 cm-sized well- encapsulated, ovoid, cystic mass. Histological examination showed a biphasic neoplasm composed of anastomosing nests of epithelial cells and somewhat cellular stromal spindle cells that had advanced degenerative changes. Immunohistochemical staining using the antibodies for cytokeratins, EMA, e-cadherin, and p75NGFR showed a strong expression of these markers in the epithelial component but no expression in the spindle stromal cells. The epithelial tumor cells showed no reactivity to CD5 and L26 and a high proportion of the infiltrated lymphocytes were the cortical type that expressed CD99 and terminal deoxynucleotidyl transferase. Ultrastructural examinations revealed tonofilaments in the spindle cells. Follow up has been done for 5 years after the surgical excision and the patient has been free of disease during that period. Similar to previous reports, this patient had a benign clinical course that was unassociated with myasthenia gravis which appears to be a characteristic of this histologic variant of thymoma. However, our case also showed advanced degenerative features and we could demonstrate ultrastructural evidence of epithelial differentiation in the stromal spindle cells that were not mentioned in the previously reported cases. Based on the results of our studies, we suggest this entity is a distinct type of organotypic thymoma that shows cortical differentiation and abundant cellular stroma.
伴有假肉瘤性间质的胸腺瘤是一种最近才被描述的罕见胸腺瘤变体，其特征是具有双相组织学模式，由上皮和梭形细胞间质成分组成。到目前为止，全世界仅报道了11例具有相似组织学表现的病例。此时，我们报告一例发生在一名53岁韩国男性身上的这种罕见胸腺瘤变体病例。这位此前健康的患者出现咳嗽症状，随后影像学检查发现前纵隔肿块。纵隔探查发现一个9×8×8厘米大小、包膜完整、椭圆形的囊性肿块。组织学检查显示为双相肿瘤，由相互吻合的上皮细胞巢和有进展性退变改变的有点细胞性的间质梭形细胞组成。使用细胞角蛋白、EMA、E-钙黏蛋白和p75NGFR抗体进行免疫组化染色显示，这些标志物在上皮成分中强烈表达，而在梭形间质细胞中无表达。上皮肿瘤细胞对CD5和L26无反应，浸润淋巴细胞中高比例为表达CD99和末端脱氧核苷酸转移酶的皮质型。超微结构检查显示梭形细胞中有张力丝。手术切除后已随访5年，在此期间患者无疾病复发。与先前报道相似，该患者临床病程良性，与重症肌无力无关，这似乎是这种胸腺瘤组织学变体的一个特征。然而，我们的病例也显示出进展性退变特征，并且我们能够证明在先前报道的病例中未提及的间质梭形细胞中有上皮分化的超微结构证据。基于我们的研究结果，我们认为该实体是一种独特类型的器官样胸腺瘤，表现为皮质分化和丰富的细胞性间质。
