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Abstract：
BACKGROUND: Epithelioid schwannoma as a rare variant poses a challenge to all pathologists, as this uncommon entity is extremely difficult to conclusively diagnose by morphological analyses on a resected sample alone owing to its unique histopathological features. However, few papers have described the detailed clinicopathological characteristics of epithelioid schwannoma.
METHODS: A 65-year-old female presented with a history of a flat and slightly elevated firm and tan plaque accompanied by occasional tenderness, measuring 10 × 8 mm, in the right joint of her hand 1 year before resection. A gross examination of a locally resected specimen revealed an encapsulated nodular lesion, yellow-whitish in color, partly filled with blood. A microscopic examination showed that the tumor predominantly consisted of a solid proliferation of epithelioid cells having mildly enlarged and round to partially spindled nuclei and abundant vacuolated or clear cytoplasm with very few mitotic figures and modest nuclear size variation, associated with focal hyalinized, cystic and hemorrhagic degeneration. This well-demarcated tumor was surrounded by dense, hyalinized and layered fibrocollagenous stroma. Immunohistochemically, these tumor cells were diffusely positive for S-100 protein and had a very low MIB-1 labeling index, and type IV collagen was strongly reactive with reduplicated basal lamina of them. We ultimately made a diagnosis of cutaneous epithelioid schwannoma.
CONCLUSIONS: We should be aware that, since pathologists might misinterpret epithelioid schwannoma as other soft tissue tumors, including its malignant counterpart, a wide panel of immunohistochemical antibodies can be powerful supplementary tools for identifying a very rare entity of conventional schwannoma.
METHODS: A 65-year-old female presented with a history of a flat and slightly elevated firm and tan plaque accompanied by occasional tenderness, measuring 10 × 8 mm, in the right joint of her hand 1 year before resection. A gross examination of a locally resected specimen revealed an encapsulated nodular lesion, yellow-whitish in color, partly filled with blood. A microscopic examination showed that the tumor predominantly consisted of a solid proliferation of epithelioid cells having mildly enlarged and round to partially spindled nuclei and abundant vacuolated or clear cytoplasm with very few mitotic figures and modest nuclear size variation, associated with focal hyalinized, cystic and hemorrhagic degeneration. This well-demarcated tumor was surrounded by dense, hyalinized and layered fibrocollagenous stroma. Immunohistochemically, these tumor cells were diffusely positive for S-100 protein and had a very low MIB-1 labeling index, and type IV collagen was strongly reactive with reduplicated basal lamina of them. We ultimately made a diagnosis of cutaneous epithelioid schwannoma.
CONCLUSIONS: We should be aware that, since pathologists might misinterpret epithelioid schwannoma as other soft tissue tumors, including its malignant counterpart, a wide panel of immunohistochemical antibodies can be powerful supplementary tools for identifying a very rare entity of conventional schwannoma.
摘要：
背景：上皮样神经鞘瘤作为一种罕见的变异体对所有病理学家构成了挑战，因为这种不常见的实体由于其独特的组织病理学特征，仅通过对切除的样品进行形态学分析很难最终诊断。然而,很少有论文描述了上皮样神经鞘瘤的详细临床病理特征。
方法：一名65岁的女性，有一个平坦的、略微隆起的坚硬和棕褐色的斑块，并伴有偶尔的压痛。测量10×8毫米，切除前1年在她手的右关节。对局部切除的标本进行粗略检查，发现包裹的结节性病变，黄色-白色，部分充满了血。显微镜检查显示，肿瘤主要由上皮样细胞的实体增殖组成，这些细胞具有轻度扩大的圆形至部分纺锤状的核和大量的空泡状或透明的细胞质，几乎没有有丝分裂图和适度的核大小变化。与局灶性透明相关，囊性和出血性变性。这个界限分明的肿瘤被致密的包围着，透明和层状纤维胶原基质。免疫组织化学，这些肿瘤细胞对S-100蛋白呈弥漫性阳性，MIB-1标记指数非常低，IV型胶原蛋白与它们的重复基底膜强烈反应。我们最终诊断为皮肤上皮样神经鞘瘤。
结论：我们应该意识到，因为病理学家可能会将上皮样神经鞘瘤误解为其他软组织肿瘤，包括它的恶性对应物，一组广泛的免疫组织化学抗体可以成为鉴定非常罕见的常规神经鞘瘤实体的强大补充工具。
方法：一名65岁的女性，有一个平坦的、略微隆起的坚硬和棕褐色的斑块，并伴有偶尔的压痛。测量10×8毫米，切除前1年在她手的右关节。对局部切除的标本进行粗略检查，发现包裹的结节性病变，黄色-白色，部分充满了血。显微镜检查显示，肿瘤主要由上皮样细胞的实体增殖组成，这些细胞具有轻度扩大的圆形至部分纺锤状的核和大量的空泡状或透明的细胞质，几乎没有有丝分裂图和适度的核大小变化。与局灶性透明相关，囊性和出血性变性。这个界限分明的肿瘤被致密的包围着，透明和层状纤维胶原基质。免疫组织化学，这些肿瘤细胞对S-100蛋白呈弥漫性阳性，MIB-1标记指数非常低，IV型胶原蛋白与它们的重复基底膜强烈反应。我们最终诊断为皮肤上皮样神经鞘瘤。
结论：我们应该意识到，因为病理学家可能会将上皮样神经鞘瘤误解为其他软组织肿瘤，包括它的恶性对应物，一组广泛的免疫组织化学抗体可以成为鉴定非常罕见的常规神经鞘瘤实体的强大补充工具。
