Abstract：
BACKGROUND: Synovial sarcomas (SS) are malignant tumors originating from pluripotent mesenchymal cells, with predilection for periarticular areas, as deep-seated soft tissue tumors. Treatment of SS of the head and neck (HN) is usually radical local excision and additional radiation or (neo)adjuvant chemotherapy or both. SS are characterized by a specific SS18-SSX1/2/4 fusion gene. SS have several morphological variants: monophasic, biphasic, or poorly differentiated.
RESULTS: We describe a SS of mandibular condyle that showed an overwhelming (>95%) epithelial cell component mimicking odontogenic carcinoma. One year prior to presentation, a woman developed a 2.5 cm destructive bone lesion in the left mandibular condyle. The initial diagnosis of ameloblastoma on biopsy was changed to odontogenic carcinoma on the surgical specimen. Four months later a computed tomography (CT) revealed local recurrence; another month later, magnetic resonance imaging (MRI) depicted a new left temporal lobe brain lesion. The patient started on a carboplatin and paclitaxel therapy, with no clinical or radiologic benefit. Subsequently she was presented for another opinion. The pathology material was re-reviewed. Fluorescence in situ hybridization (FISH) resulted a positive result for SS18 (SYT) rearrangement; next generation sequencing (NGS sarcoma fusion panel) reported an SS18-SSX2 fusion transcript. Based on molecular testing the tumor was reclassified as synovial sarcoma. Her systemic treatment was changed to anthracycline based systemic therapy.
CONCLUSIONS: This case emphasizes the importance of molecular approaches in diagnostic pathology. Accurate diagnosis is imperative to avoid misclassification as carcinoma (metastasis or primary e.g., odontogenic carcinoma), carcinosarcoma or a different sarcoma type with epithelioid or epithelial differentiation and to determine proper treatment.
RESULTS: We describe a SS of mandibular condyle that showed an overwhelming (>95%) epithelial cell component mimicking odontogenic carcinoma. One year prior to presentation, a woman developed a 2.5 cm destructive bone lesion in the left mandibular condyle. The initial diagnosis of ameloblastoma on biopsy was changed to odontogenic carcinoma on the surgical specimen. Four months later a computed tomography (CT) revealed local recurrence; another month later, magnetic resonance imaging (MRI) depicted a new left temporal lobe brain lesion. The patient started on a carboplatin and paclitaxel therapy, with no clinical or radiologic benefit. Subsequently she was presented for another opinion. The pathology material was re-reviewed. Fluorescence in situ hybridization (FISH) resulted a positive result for SS18 (SYT) rearrangement; next generation sequencing (NGS sarcoma fusion panel) reported an SS18-SSX2 fusion transcript. Based on molecular testing the tumor was reclassified as synovial sarcoma. Her systemic treatment was changed to anthracycline based systemic therapy.
CONCLUSIONS: This case emphasizes the importance of molecular approaches in diagnostic pathology. Accurate diagnosis is imperative to avoid misclassification as carcinoma (metastasis or primary e.g., odontogenic carcinoma), carcinosarcoma or a different sarcoma type with epithelioid or epithelial differentiation and to determine proper treatment.
摘要：
背景：滑膜肉瘤（SS）是起源于多能间充质细胞的恶性肿瘤，对关节周围区域有利，深层软组织肿瘤.头颈部（HN）SS的治疗通常是根治性局部切除和额外的放射或（新）辅助化疗或两者兼而有之。SS的特征在于特异性SS18-SSX1/2/4融合基因。SS有几种形态变异：单相，双相,或者分化差。
结果：我们描述了下颌髁突的SS，显示出压倒性的（>95％）上皮细胞成分模仿牙源性癌。在演讲前一年，一名妇女在左下颌髁突出现2.5厘米的破坏性骨损伤。活检时成釉细胞瘤的最初诊断改为手术标本上的牙源性癌。四个月后，计算机断层扫描（CT）显示局部复发；一个月后，磁共振成像（MRI）描绘了一个新的左颞叶脑病变。患者开始接受卡铂和紫杉醇治疗，没有临床或放射学益处。随后，她被提出另一种意见。重新审查病理材料。荧光原位杂交（FISH）对SS18（SYT）重排产生阳性结果；下一代测序（NGS肉瘤融合组）报告了SS18-SSX2融合转录本。根据分子测试，将肿瘤重新分类为滑膜肉瘤。她的全身治疗改为基于蒽环类的全身治疗。
结论：本案例强调了分子方法在病理诊断中的重要性。准确的诊断是必要的，以避免错误分类为癌症（转移或原发，例如，牙源性癌)，癌肉瘤或具有上皮样或上皮分化的不同类型的肉瘤，并确定适当的治疗方法。
结果：我们描述了下颌髁突的SS，显示出压倒性的（>95％）上皮细胞成分模仿牙源性癌。在演讲前一年，一名妇女在左下颌髁突出现2.5厘米的破坏性骨损伤。活检时成釉细胞瘤的最初诊断改为手术标本上的牙源性癌。四个月后，计算机断层扫描（CT）显示局部复发；一个月后，磁共振成像（MRI）描绘了一个新的左颞叶脑病变。患者开始接受卡铂和紫杉醇治疗，没有临床或放射学益处。随后，她被提出另一种意见。重新审查病理材料。荧光原位杂交（FISH）对SS18（SYT）重排产生阳性结果；下一代测序（NGS肉瘤融合组）报告了SS18-SSX2融合转录本。根据分子测试，将肿瘤重新分类为滑膜肉瘤。她的全身治疗改为基于蒽环类的全身治疗。
结论：本案例强调了分子方法在病理诊断中的重要性。准确的诊断是必要的，以避免错误分类为癌症（转移或原发，例如，牙源性癌)，癌肉瘤或具有上皮样或上皮分化的不同类型的肉瘤，并确定适当的治疗方法。
