摘要目的:探讨CRTC1：：TRIM11融合性皮肤黑色素细胞肿瘤（cutaneous melanocytic tumor with CRTC1：：TRIM11 fusion，CMTCT）的临床病理学特征、诊断及鉴别诊断要点，提高对该肿瘤的认识。方法:收集佛山市中医院及济南金域医学检验中心诊断的CMTCT 3例，分析患者的临床特征及病理形态学、免疫组织化学、分子特点并文献复习。结果:本组3例CMTCT均为女性，例1、2、3年龄分别是53、46、46岁，大体表现为真皮/皮下结节，突出于皮面。组织学瘤细胞呈巢状、束状排列，巢、束间可见纤细的纤维间隔。例2、3表皮未见肿瘤细胞浸润，例1表皮受累及，瘤细胞呈上皮样、梭形或卵圆形，胞质嗜酸性或淡染，细胞核有轻至中度异型性，核分裂象<5个/10 HPF。例2间质中可见少许黑色素颗粒。免疫组织化学显示SOX10、S-100蛋白、MITF均弥漫强阳性；HMB45阴性2例（例1和例3），1例（例2）散在阳性；Melan A阴性2例（例1和例3），1例（例2）部分阳性；Ki-67阳性指数5%~8%。分子特征：3例RNA测序显示CRTC1：：TRIM11融合，2例（例1和例3）荧光原位杂交显示CRTC1断裂阳性。结论:CMTCT组织学形态及免疫表型与黑色素瘤及透明细胞肉瘤存在重叠，其特征性具有CRTC1：：TRIM11基因融合，分子检测是确诊的关键。肿物需完整切除并保证切缘干净，多数CMTCT生物学行为较为惰性，少数病例可局部复发或转移，需长期随访。

abstractsObjective:To investigate the clinicopathological characteristics and diagnostic criteria of cutaneous melanocytic tumor with CRTC1::TRIM11 fusion (CMTCT), and to improve understanding of this entity.Methods:The clinical features, histology, immunohistochemistry (IHC) and molecular characteristics of 3 CMTCT cases were analyzed, supplemented by a literature review.Results:All patients were female, aged 53, 46 and 46 years, respectively. Grossly, the lesions presented as dermal/subcutaneous nodules protruding from the skin surface. Histologically, tumor cells were arranged in nested and fascicular patterns separated by delicate fibrous septa. Tumor cell infiltration was observed in the epidermis of case 1, but not in that of cases 2 and 3. Tumor cells exhibited epithelioid, spindle-shaped, or oval morphology, with eosinophilic or pale cytoplasm and mild to moderate nuclear atypia. Tumor mitotic figure was <5/10 HPF. Scant melanin pigment was observed in case 2. IHC demonstrated diffuse and strong positivity for SOX-10, S-100 protein and MITF. HMB45 was negative in two cases (case 1 and case 3) and focally positive in case 2; Melan A was negative in two cases (case 1 and case 3) and partially positive in case 2. The Ki-67 proliferation index was approximately 5%-8%. Molecular analysis revealed CRTC1::TRIM11 fusion in three cases via RNA sequencing, and CRTC1 rearrangement in two cases (case 1 and case 3) via fluorescence in situ hybridization.Conclusions:CMTCT shares histological and immunophenotypic features with melanoma and clear cell sarcoma but is defined by the presence of CRTC1::TRIM11 fusion, necessitating molecular confirmation for definitive diagnosis. Complete excision with clear margins is recommended. While most of the CMTCTs exhibit indolent biological behaviors, rare cases may recur locally or metastasize, warranting close follow-up.