PEComa 肿瘤家族由具有肌黑素细胞分化的梭形/上皮样细胞定义。一小部分包含 TFE3 融合；然而，YAP1::TEE3 尚未被报道。肺透明细胞间质瘤 (CCST-L) 是一种新兴实体，其特征为梭形至上皮样细胞，伴有局灶性细胞质透明、炎症浸润、无肌黑素细胞分化和 YAP1::TFE3 融合。在此，我们报告两例伴有肌黑细胞分化的肺部肿瘤，显示炎性梭形细胞组织学、局灶性上皮样透明细胞以及 YAP1::TFE3 融合。患者均为男性，年龄分别为 61 岁和 68 岁。两例肿瘤均表现为边界清楚的实性肿块，累及肺门。肺叶切除术后，7 个月和 32 个月未观察到复发。两种肿瘤均具有长梭形细胞的席纹状至短束状生长，在大量瘤内慢性炎症和扩张的血管的背景下，上皮样细胞的少量成分显示出透明的细胞质。一个肿瘤显示局灶性黑色素沉积。两种肿瘤的 HMB45、Melan A 和 h-caldesmon 免疫组织化学结果均呈阳性。荧光原位杂交检测表明存在 YAP1::TFE3 融合体，这一点通过 1 例测试病例的 RNA 测序以及免疫组织化学 TFE3 表达和 YAP1 C 末端染色的缺失得到证实。我们介绍了两例上皮样细胞炎性纺锤体的病例具有肌黑素细胞分化和 YAP1::TFE3 融合的肺部肿瘤。这种独特的形态和基因融合表明这些肿瘤可能构成肺 PEComa 的一个独特亚型。此外，与 CCST-L 的形态和分子重叠产生了 PEComa 和 CCST-L 之间潜在内在关系的假设。© 2024 John Wiley

The PEComa family of tumours is defined by spindle/epithelioid cells with myomelanocytic differentiation. A small subset harbours TFE3 fusion; however, YAP1::TEE3 has not been reported. Clear cell stromal tumour of the lung (CCST-L) is an emerging entity characterized by spindle to epithelioid cells with focal cytoplasmic clearing, inflammatory infiltrates, no myomelanocytic differentiation, and YAP1::TFE3 fusion. Herein, we report two cases of lung tumours with myomelanocytic differentiation that showed inflammatory spindle cell histology, focal epithelioid clear cells, as well as YAP1::TFE3 fusion.The patients were both men, aged 61 and 68 years. The tumours in both cases presented as well-circumscribed solid masses involving the lung hilum. After lobectomy, no recurrence was observed at 7 and 32 months. Both tumours shared storiform to short fascicular growth of long spindle cells, with a minor component of epithelioid cells showing clear cytoplasm in the background of substantial intratumoral chronic inflammation and dilated blood vessels. One tumour showed focal melanin deposition. Both tumours were immunohistochemically positive for HMB45, Melan A, and h-caldesmon. Fluorescence in situ hybridization assays indicated the presence of YAP1::TFE3 fusions, which was confirmed by RNA sequencing in one case tested, and by immunohistochemical TFE3 expression and loss of YAP1 C-terminus staining.We present two cases of inflammatory spindle to epithelioid cell tumours of the lungs with myomelanocytic differentiation and YAP1::TFE3 fusion. This unique morphology and gene fusion suggest that these tumours may constitute a distinct subset of lung PEComa. Furthermore, morphological and molecular overlap with CCST-L gives rise to a hypothesis of a potential inherent relationship between PEComa and CCST-L.© 2024 John Wiley & Sons Ltd.