PDF(Pubmed)
Abstract：
OBJECTIVE: Hybrid nerve sheath tumor (HNST) is a benign peripheral nerve sheath tumor with combined features of more than one histological type, such as schwannoma, neurofibroma, and perineurioma. It remains under-recognized in routine clinical practice. Herein, we describe an unusual case of intramuscular HNST of the thigh.
METHODS: The patient was a 41-year-old man with no history of trauma who presented with a 3-month history of a palpable mass in the right thigh. Physical examination revealed a 4-cm, elastic hard, mobile, nontender mass. Magnetic resonance imaging exhibited a well-circumscribed intramuscular mass with low-to-intermediate signal intensity on T1-weighted sequences and higher signal intensity peripherally and lower signal intensity centrally, representing a target sign, on T2-weighted sequences. Complete surgical excision of the tumor was carried out. Microscopically, the tumor showed dual histological components of both schwannoma and neurofibroma. Immunohistochemically, the schwannomatous component was strongly and diffusely positive for S-100 protein and negative for CD34, while the neurofibromatous component contained CD34-positive fibroblasts and S-100 protein-positive Schwann cells. Epithelial membrane antigen was negative for both components. These findings were consistent with a diagnosis of HNST (hybrid schwannoma/neurofibroma). The patient had no evidence of local recurrence and no neurological deficit at the final follow-up.
CONCLUSIONS: Although extremely rare, HNST should be included in the extended differential diagnosis of a well-circumscribed, intramuscular soft-tissue mass in the extremities, particularly in young and early middle-aged adults.
METHODS: The patient was a 41-year-old man with no history of trauma who presented with a 3-month history of a palpable mass in the right thigh. Physical examination revealed a 4-cm, elastic hard, mobile, nontender mass. Magnetic resonance imaging exhibited a well-circumscribed intramuscular mass with low-to-intermediate signal intensity on T1-weighted sequences and higher signal intensity peripherally and lower signal intensity centrally, representing a target sign, on T2-weighted sequences. Complete surgical excision of the tumor was carried out. Microscopically, the tumor showed dual histological components of both schwannoma and neurofibroma. Immunohistochemically, the schwannomatous component was strongly and diffusely positive for S-100 protein and negative for CD34, while the neurofibromatous component contained CD34-positive fibroblasts and S-100 protein-positive Schwann cells. Epithelial membrane antigen was negative for both components. These findings were consistent with a diagnosis of HNST (hybrid schwannoma/neurofibroma). The patient had no evidence of local recurrence and no neurological deficit at the final follow-up.
CONCLUSIONS: Although extremely rare, HNST should be included in the extended differential diagnosis of a well-circumscribed, intramuscular soft-tissue mass in the extremities, particularly in young and early middle-aged adults.
摘要：
目的：混合神经鞘瘤（HNST）是一种良性周围神经鞘瘤，具有多种组织学类型的综合特征，比如神经鞘瘤,神经纤维瘤,和神经鞘瘤.在常规临床实践中仍未得到充分认可。在这里，我们描述了一个不寻常的大腿肌内HNST病例。
方法：患者为一名41岁男性，无外伤史，有3个月的右侧大腿肿块病史。体格检查显示有4厘米，弹性硬，mobile,非招标质量。磁共振成像表现出界限良好的肌内肿块，在T1加权序列上具有低至中等的信号强度，在外周具有较高的信号强度，在中央具有较低的信号强度，代表一个目标标志，在T2加权序列上。对肿瘤进行了完整的手术切除。微观上,肿瘤显示神经鞘瘤和神经纤维瘤的双重组织学成分。免疫组织化学，神经鞘瘤成分对S-100蛋白呈强烈和弥漫性阳性,对CD34呈阴性,而神经纤维瘤成分含有CD34阳性成纤维细胞和S-100蛋白阳性雪旺氏细胞.两种成分的上皮膜抗原均为阴性。这些发现与HNST（混合神经鞘瘤/神经纤维瘤）的诊断一致。在最后一次随访中，患者没有局部复发的证据，也没有神经功能缺损。
结论：虽然极为罕见，HNST应包括在界限明确的扩展鉴别诊断中，四肢肌内软组织肿块，尤其是年轻和早期的中年人。
方法：患者为一名41岁男性，无外伤史，有3个月的右侧大腿肿块病史。体格检查显示有4厘米，弹性硬，mobile,非招标质量。磁共振成像表现出界限良好的肌内肿块，在T1加权序列上具有低至中等的信号强度，在外周具有较高的信号强度，在中央具有较低的信号强度，代表一个目标标志，在T2加权序列上。对肿瘤进行了完整的手术切除。微观上,肿瘤显示神经鞘瘤和神经纤维瘤的双重组织学成分。免疫组织化学，神经鞘瘤成分对S-100蛋白呈强烈和弥漫性阳性,对CD34呈阴性,而神经纤维瘤成分含有CD34阳性成纤维细胞和S-100蛋白阳性雪旺氏细胞.两种成分的上皮膜抗原均为阴性。这些发现与HNST（混合神经鞘瘤/神经纤维瘤）的诊断一致。在最后一次随访中，患者没有局部复发的证据，也没有神经功能缺损。
结论：虽然极为罕见，HNST应包括在界限明确的扩展鉴别诊断中，四肢肌内软组织肿块，尤其是年轻和早期的中年人。
