Abstract：
Perivascular epithelioid cell tumors (PEComas) are a family of benign neoplasms characterized by smooth muscle and melanocytic differentiation. Orbital cases are rare. A 9-year-old male presented with a slowly growing orbital mass. Magnetic resonance imaging (MRI) revealed a well-defined orbital mass without intracranial extension. The microscopic appearance of the complete resection specimen showed large nests of epithelioid cells with wide cytoplasm containing melanin pigment and round to oval nuclei with mild cytonuclear atypia and low mitotic activity. Immunohistochemistry was positive for HMB45 and negative for melanA, smooth muscle actin, desmin and S-100 protein. Pangenomic RNA-sequencing identified an in-frame NONO-TFE3 rearrangement, and clustering data showed that the tumor\'s gene expression profile was grouped with other previously studied PEComas. A diagnosis of orbital pigmented PEComa with uncertain malignant potential associated with a NONO-TFE3 rearrangement was made. There was no recurrence after 1 year of follow-up.
摘要：
血管周围上皮样细胞肿瘤（PEComas）是一类以平滑肌和黑素细胞分化为特征的良性肿瘤。轨道病例很少见。一名9岁男性眼眶质量缓慢增长。磁共振成像（MRI）显示明确的眼眶肿块，无颅内扩展。完整切除标本的微观外观显示上皮样细胞的大巢，具有包含黑色素的宽细胞质和圆形至椭圆形核，具有轻度的细胞核异型性和低有丝分裂活性。免疫组化HMB45阳性，黑色素A阴性，平滑肌肌动蛋白，desmin和S-100蛋白。PangenomicRNA测序鉴定了框内的NONO-TFE3重排，和聚类数据显示，肿瘤的基因表达谱与其他先前研究的PEComas分组。诊断患有与NONO-TFE3重排相关的不确定恶性潜能的眼眶色素PEComa。随访1年后无复发。
