Yoshida Hiroshi, Saito Ayumi
Department of Diagnostic Pathology, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-Ku, Tokyo, 104-0045, Japan.
Department of Medical Oncology, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-Ku, Tokyo, 104-0045, Japan.
Virchows Arch. 2025 Sep 1. doi: 10.1007/s00428-025-04238-8.
Myoepithelial carcinoma (MECA) is a rare malignant tumor showing myoepithelial differentiation, most commonly found in the salivary glands and soft tissue, with only isolated reports in the female genital tract. We report the first documented case of uterine MECA harboring an EWSR1::ZNF444 fusion. A 55-year-old woman with a history of breast cancer presented with abnormal uterine bleeding. Imaging suggested a benign lesion, but hysteroscopic resection raised suspicion for uterine sarcoma. Hysterectomy revealed an infiltrative neoplasm composed of epithelioid and spindle cells with focal osseous differentiation. Immunohistochemistry showed focal positivity for αSMA, desmin, AE1/AE3, CAM5.2, and S100. Recurrent disease in lymph nodes and omentum showed a similar phenotype. FISH demonstrated EWSR1 rearrangement, and RNA sequencing identified an in-frame EWSR1::ZNF444 fusion, confirming the diagnosis of MECA. The tumor recurred twice over two years, reflecting aggressive behavior. While MECA typically arises in salivary glands and soft tissue, this case expands its anatomical spectrum to the uterus. This report underscores the importance of molecular diagnostics in classifying rare uterine mesenchymal tumors and highlights the diagnostic challenges posed by their broad morphological and immunophenotypic overlap with other entities.
肌上皮癌（MECA）是一种罕见的具有肌上皮分化的恶性肿瘤，最常见于唾液腺和软组织，在女性生殖道仅有个别报道。我们报告首例记录在案的子宫MECA病例，该病例存在EWSR1::ZNF444融合基因。一名有乳腺癌病史的55岁女性出现子宫异常出血。影像学检查提示为良性病变，但宫腔镜切除术后引发了子宫肉瘤的怀疑。子宫切除标本显示为浸润性肿瘤，由上皮样细胞和梭形细胞组成，伴有局灶性骨分化。免疫组化显示αSMA、结蛋白、AE1/AE3、CAM5.2和S100呈局灶阳性。淋巴结和大网膜的复发病变表现出相似的表型。荧光原位杂交（FISH）显示EWSR1重排，RNA测序鉴定出一个符合读框的EWSR1::ZNF444融合基因，确诊为MECA。该肿瘤在两年内复发两次，显示出侵袭性行为。虽然MECA通常发生于唾液腺和软组织，但本病例将其解剖学范围扩展至子宫。本报告强调了分子诊断在罕见子宫间叶性肿瘤分类中的重要性，并突出了其与其他实体在广泛的形态学和免疫表型重叠方面所带来的诊断挑战。
