Mikami Toshinari, Kurose Akira, Javed Fawad, Takeda Yasunori
Associate Professor, Division of Anatomical and Cellular Pathology, Department of Pathology, Iwate Medical University, Iwate, Japan.
Professor, Department of Anatomic Pathology, Hirosaki University Graduate School of Medicine, Aomori, Japan.
J Oral Maxillofac Surg. 2015 Aug;73(8):1505-15. doi: 10.1016/j.joms.2015.02.010. Epub 2015 Mar 16.
Synovial sarcoma (SS) accounts for 5 to 10% of soft tissue sarcomas; however, intraoral SS is rare. Histopathologically, SS shows a biphasic pattern with epithelial and spindle cell components or a monophasic pattern with only spindle cells. The precise diagnosis of SS, especially at an unusual site, is often a challenge to pathologists and clinical oncologists, because the differential diagnosis of SS includes a broad range of tumors, such as soft tissue sarcomas and carcinomas. In the present case, the patient was a 50-year-old woman who presented with the chief complaint of swelling and a slowly enlarging mass of the lower lip in the mucolabial fold region. The mass was covered with intact mucosa and intraoral examination showed no malignant findings. The clinical diagnosis was a benign tumor and a probable salivary gland tumor. Macroscopically, the excised mass also indicated a benign tumor; however, histopathologic findings suggested the diagnosis of SS. For definitive diagnosis, genetic analyses were performed with conventional polymerase chain reaction and next-generation sequencing. As a result, a rare variant of the SS18-SSX1 fusion transcript, which could not be identified by routine procedures for genetic diagnosis, was detected. In addition, 8 missense mutations of cancer-related genes were confirmed. Detection of the fusion transcript is widely used in the diagnosis of SS; however, reported cases of transcript variants of each fusion gene type are limited. Reports of mutational analysis of cancer-related genes on SS also are rare. The accumulation of rare transcript variants and the cytogenetic characters of SS are suggested to be necessary for assuming a genetic diagnosis of SS.
滑膜肉瘤（SS）占软组织肉瘤的5%至10%；然而，口腔内滑膜肉瘤较为罕见。在组织病理学上，滑膜肉瘤表现为具有上皮和梭形细胞成分的双相模式或仅具有梭形细胞的单相模式。滑膜肉瘤的准确诊断，尤其是在不寻常部位时，对病理学家和临床肿瘤学家来说往往是一项挑战，因为滑膜肉瘤的鉴别诊断包括多种肿瘤，如软组织肉瘤和癌。在本病例中，患者为一名50岁女性，主要症状为下唇唇黏膜褶区域肿胀及肿物缓慢增大。肿物表面黏膜完整，口腔检查未发现恶性表现。临床诊断为良性肿瘤，可能为涎腺肿瘤。大体检查时，切除的肿物也提示为良性肿瘤；然而，组织病理学检查结果提示为滑膜肉瘤。为明确诊断，采用传统聚合酶链反应和下一代测序进行基因分析。结果，检测到一种罕见的SS18 - SSX1融合转录变体，这是常规基因诊断程序无法识别的。此外，还确认了8个癌症相关基因的错义突变。融合转录体的检测在滑膜肉瘤诊断中广泛应用；然而，每种融合基因类型转录变体的报道病例有限。关于滑膜肉瘤癌症相关基因突变分析的报道也很少。提示罕见转录变体的积累和滑膜肉瘤的细胞遗传学特征对于滑膜肉瘤的基因诊断很有必要。
