Hisaoka Masanori, Matsuyama Atsuji, Shimajiri Shohei, Akiba Jun, Kusano Hironori, Hiraoka Koji, Shoda Takanori, Hashimoto Hiroshi
Department of Pathology and Oncology, School of Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu 807-8555, Japan.
Pathol Res Pract. 2009;205(3):195-8. doi: 10.1016/j.prp.2008.10.003. Epub 2008 Nov 28.
Although intralesional calcification is a common finding of synovial sarcoma, ossification is an unusual phenomenon in such a soft tissue sarcoma. Here we report a case of ossifying synovial sarcoma arising in the back of a young adult man. Microscopically, the tumor was composed of spindle or oval cells together with foci of atypical polygonal cells in small nests or cord-like structures, displaying an epithelial appearance. In addition, extensive osteoid or woven bone formation was present in the tumor, resembling extraskeletal osteosarcoma. However, an SS18-SSX1 fusion gene transcript was detected by reverse transcription-polymerase chain reaction, supporting the diagnosis of biphasic synovial sarcoma. The osteogenic phenotype of the tumor cells was further demonstrated by an intense immunohistochemical expression of Runx2, a key transcription factor involved in the regulation of osteoblastic differentiation. The current case suggests the diagnostic utility of the molecular detection of a tumor type-specific fusion gene and expands the phenotypic plasticity of the soft tissue sarcoma of uncertain differentiation.
尽管瘤内钙化是滑膜肉瘤的常见表现，但骨化在这种软组织肉瘤中是一种不寻常的现象。在此，我们报告一例发生于一名年轻成年男性背部的骨化性滑膜肉瘤病例。显微镜下，肿瘤由梭形或椭圆形细胞以及小巢状或条索状结构中的非典型多边形细胞灶组成，呈现上皮样外观。此外，肿瘤内存在广泛的类骨质或编织骨形成，类似于骨外骨肉瘤。然而，通过逆转录 - 聚合酶链反应检测到SS18 - SSX1融合基因转录本，支持双相滑膜肉瘤的诊断。Runx2是参与成骨细胞分化调控的关键转录因子，其免疫组化强烈表达进一步证明了肿瘤细胞的成骨表型。本例提示肿瘤类型特异性融合基因的分子检测在诊断中的应用价值，并扩展了未分化软组织肉瘤的表型可塑性。
