Preferentially expressed antigen in melanoma (PRAME) is considered a useful marker in the differential diagnosis between malignant melanoma and its melanocytic mimics. Recently PRAME expression was documented in nonmelanocytic tumors, but much of the data are based on mRNA studies. This investigation evaluated PRAME expression in the spectrum of normal tissues and >5800 human tumors using immunohistochemistry and EP461 monoclonal antibody. In normal tissues, PRAME was expressed in the testis and proliferative endometrium. In tumors, PRAME was variably expressed in malignancies of different lineages. Among epithelial tumors, >50% of PRAME-positive lesions were found among endometrial carcinomas (82%), uterine serous carcinomas (82%), uterine carcinosarcomas (60%), ovarian clear cell carcinomas (90%), ovarian serous carcinomas (63%), adenoid cystic carcinomas (81%), seminomas (78%), thymic carcinomas (75%), and basal cell carcinomas (62%). In mesenchymal and neuroectodermal malignancies, PRAME was frequently expressed in synovial sarcoma (71%), myxoid liposarcoma (76%), neuroblastoma (61%) and metastatic melanoma (87%). Also, PRAME was consistently expressed in 4 melanomas that lacked all melanoma markers including S100 protein and SOX10 but harbored typical for melanoma BRAF or NRAS driver mutations. However, strong and diffuse PRAME immunoreactivity was seen in many types of nonmelanocytic poorly differentiated carcinomas and sarcomas. Based on this study, PRAME is a relatively unspecific immunohistochemical marker, which limits its use in diagnostic surgical pathology. However, immunohistochemistry is a reliable and unexpensive method useful in detecting PRAME-positive malignancies for potential immunotherapy.

黑色素瘤中优先表达的抗原（PRAME）被认为是鉴别诊断恶性黑色素瘤及其黑素细胞模拟物的有用标志物。最近在非黑素细胞肿瘤中记录了 PRAME 表达，但大部分数据基于 mRNA 研究。这项研究使用免疫组织化学和 EP461 单克隆抗体评估了正常组织和超过 5800 个人类肿瘤中的 PRAME 表达。在正常组织中，PRAME在睾丸和增殖期子宫内膜中表达。在肿瘤中，PRAME 在不同谱系的恶性肿瘤中表达不同。在上皮性肿瘤中，>50%的PRAME阳性病变见于子宫内膜癌（82%）、子宫浆液性癌（82%）、子宫癌肉瘤（60%）、卵巢透明细胞癌（90%）、卵巢浆液性癌（ 63%）、腺样囊性癌（81%）、精原细胞瘤（78%）、胸腺癌（75%）和基底细胞癌（62%）。在间充质和神经外胚层恶性肿瘤中，PRAME 在滑膜肉瘤 (71%)、粘液样脂肪肉瘤 (76%)、神经母细胞瘤 (61%) 和转移性黑色素瘤 (87%) 中频繁表达。此外，PRAME 在 4 种黑色素瘤中一致表达，这些黑色素瘤缺乏包括 S100 蛋白和 SOX10 在内的所有黑色素瘤标志物，但具有黑色素瘤 BRAF 或 NRAS 驱动突变的典型特征。然而，在许多类型的非黑素细胞低分化癌和肉瘤中观察到强烈且弥漫的 PRAME 免疫反应性。根据这项研究，PRAME 是一种相对非特异性的免疫组织化学标记物，这限制了其在诊断外科病理学中的应用。然而，免疫组织化学是一种可靠且廉价的方法，可用于检测 PRAME 阳性恶性肿瘤以进行潜在的免疫治疗。