Tsubochi Hiroyoshi, Endo Tetsuya, Sogabe Masaya, Endo Shunsuke, Morinaga Shojiroh, Dobashi Yoh
Department of Thoracic Surgery, Saitama Medical Center, Jichi Medical University Saitama, Japan.
Department of Diagnostic Pathology, Kitasato Institute Hospital Tokyo, Japan.
Int J Clin Exp Pathol. 2014 Oct 15;7(11):7477-84. eCollection 2014.
Solitary fibrous tumor is a rare mesenchymal neoplasm, characterized by peculiar histological features composed by the proliferation of spindle cells in "patternless pattern". Although it has been known to sometimes be accompanied by epithelioid cells, the presence of a well-formed epithelial structure is far more rare. We describe herein the case of a 60-year-old female with the radiological finding of a single nodular lesion in the anterior mediastinum. Histopathological examination of the surgically resected specimen led to the diagnosis of solitary fibrous tumor of the thymus with a spectrum of well-formed epithelial components: i) glandular structure, reminiscent of breast or eccrine gland, ii) neural tube-like structure, and iii) clusters of endocrine-like cells. Immunohistochemical analysis revealed that the spindle cells expressed CD34, vimentin, bcl-2 and Stat-6, but not keratin (cytokeratin-AE1/AE3) or epithelial membrane antigen. In contrast, the epithelial components lost expression of most of these marker proteins, including Stat-6, but continued to express vimentin and strongly expressed keratin. Since no relevant past literature was found, the current case could be interpreted as a unique and previously undescribed variant of solitary fibrous tumor comprising conventional spindle cells with a spectrum of well-formed epithelial components. Pathogenesis that may have given rise to these variegated mixtures of spindle cells and epithelial components in a single tumor is also discussed.
孤立性纤维瘤是一种罕见的间叶性肿瘤，其特征为具有独特的组织学特征，由呈“无模式模式”增殖的梭形细胞组成。尽管已知其有时会伴有上皮样细胞，但具有完整上皮结构的情况更为罕见。我们在此描述了一例60岁女性患者，其影像学检查发现前纵隔有单个结节性病变。对手术切除标本进行组织病理学检查后诊断为胸腺孤立性纤维瘤，伴有一系列完整的上皮成分：i）腺管结构，类似乳腺或小汗腺；ii）神经管样结构；iii）内分泌样细胞簇。免疫组织化学分析显示，梭形细胞表达CD34、波形蛋白、bcl-2和Stat-6，但不表达角蛋白（细胞角蛋白-AE1/AE3）或上皮膜抗原。相反，上皮成分失去了这些标记蛋白中的大多数表达，包括Stat-6，但继续表达波形蛋白并强烈表达角蛋白。由于未发现相关既往文献，本病例可被解释为一种独特的、先前未描述的孤立性纤维瘤变体，由具有一系列完整上皮成分的传统梭形细胞组成。本文还讨论了可能导致单个肿瘤中出现这些梭形细胞和上皮成分杂合混合的发病机制。
