角蛋白阳性的纤维性骨外黏液样软骨肉瘤：与肌上皮瘤密切相似。
Keratin-positive fibrotic extraskeletal myxoid chondrosarcoma: a close mimic of myoepithelial tumour.
发表日期：2023 Feb 08
作者：
Hirokazu Sugino, Shintaro Iwata, Kaishi Satomi, Taisuke Mori, Sumihito Nobusawa, Toshiteru Nagashima, Yuko Matsushita, Yasushi Yatabe, Koichi Ichimura, Akira Kawai, Akihiko Yoshida
来源：
HISTOPATHOLOGY
摘要：
Extraskeletal myxoid chondrosarcoma (EMC) 是一种罕见的成人肉瘤，具有独特的组织学和 NR4A3 基因融合。免疫组织化学上，EMC 可变阳性表达 S100 蛋白和神经内分泌标记物。与组织学相似的软组织肌上皮瘤不同，角蛋白表达很少。由于最近发现两例具有弥漫性角蛋白表达的 EMC 病例，我们研究了分子学确认的 EMC 患者中上皮标记物的表达，并鉴定了另外两例相似的病例。四例角蛋白阳性的 EMC 发生在一名男性和三名年龄在 46-59 岁之间的女性身上。所有肿瘤都显示非典型的组织学，具有突出的间质纤维化，角蛋白 AE1/AE3 被表达为弥漫性 (N=2) 或局部性 (N=2)。在一例肿瘤中，角蛋白的表达仅限于硬化区域。所有肿瘤都共表达上皮膜抗原，其中两个额外表达 S100 蛋白或神经胶质酸性蛋白。所有肿瘤都携带 NR4A3 融合，包括 TAF15::NR4A3 (N=1) 和 EWSR1::NR4A3 (N=3)。最初有两例肿瘤被认为最符合肌上皮瘤，基于广泛的间质纤维化和角蛋白表达。DNA 甲基化分析将两个肿瘤分类为 EMC。我们鉴定了一小部分表达角蛋白和突出的间质纤维化具有 EMC 特征。这种组织学模式必须在肌上皮瘤的鉴别诊断中得到认识，因为误分类可能导致肿瘤行为的错误预测，并可能改变患者的管理。即使出现角蛋白表达和明显的间质纤维化，也应考虑 NR4A3 基因分析。© 2023 John Wiley & Sons Ltd.
Extraskeletal myxoid chondrosarcoma (EMC) is a rare form of adult sarcoma with distinct histology and NR4A3 gene fusion. Immunohistochemically, EMCs are variably positive for S100 protein and neuroendocrine markers. Unlike histologically similar soft-tissue myoepithelial tumours, keratin expression is rare. Prompted by two recent EMC cases with diffuse keratin expression, we investigated the expression of epithelial markers in a molecularly confirmed cohort of EMC and identified two additional similar cases.Four keratin-positive EMCs occurred in one man and three women aged 46-59 years. All tumours displayed nonclassic histology with prominent stromal fibrosis, and keratin AE1/AE3 was expressed either diffusely (N = 2) or focally (N = 2). In one tumour, keratin expression was limited to the sclerotic area. All tumours coexpressed epithelial membrane antigen and two additionally expressed S100 protein or glial fibrillary acidic protein. All tumours harboured NR4A3 fusions, including TAF15::NR4A3 (N = 1) and EWSR1::NR4A3 (N = 3). Two cases were initially considered as most consistent with myoepithelial tumours based on widespread stromal fibrosis and keratin expression. DNA methylation analysis classified two tumours tested as EMCs.We identified a small subset of EMCs characterised by keratin expression and prominent stromal fibrosis. This histological pattern must be recognised in the differential diagnosis of myoepithelial tumours because misclassification may lead to the erroneous prediction of tumour behaviour and may alter patient management. NR4A3 genetic analysis should be considered even in the face of keratin expression and prominent stromal fibrosis.© 2023 John Wiley & Sons Ltd.