Department of Pathology, Indiana University School of Medicine, Indianapolis, Indiana, USA.
Department of Pathology, University of Michigan-Michigan Medicine, Ann Arbor, Michigan, USA.
Diagn Cytopathol. 2024 Jul;52(7):362-368. doi: 10.1002/dc.25313. Epub 2024 Apr 1.
Preferentially expressed antigen in melanoma (PRAME) has been introduced as a new melanoma marker and potential target for immunotherapy. While PRAME immunohistochemistry (IHC) is well documented in surgical pathology, similar data in cytology are limited. Metastatic melanoma is frequently diagnosed via cytology samples in which IHC plays an important role. We aimed to accordingly evaluate the performance of PRAME IHC in diagnosing metastatic melanoma in cytology samples relative to other commonly used melanoma markers.
The study included 156 archival cytology cases, of which 93 were melanoma cases and 63 nonmelanoma cases (controls). All cases underwent PRAME IHC staining on cell blocks. Nuclear staining of PRAME was evaluated using a quantitative and qualitative scale. Other melanocytic IHC stain results (SOX10, S-100, Melan-A, and HMB45) were also documented.
PRAME was detected in tumor cells in 86% of melanoma cases, which was significantly lower than SOX10 (100%) (p < .01), and similar to HMB45 (84%) and Melan-A (82%). S-100 had the lowest sensitivity of 71%. In comparison to other types of melanomas, spindle cell melanoma exhibited higher negativity for PRAME IHC (4/10 = 40%). PRAME was also expressed in some nonmelanocytic malignancies including carcinoma (5/22 = 23%), sarcoma (5/15 = 33%), and hematologic malignancies (1/9 = 11%). Overall, PRAME showed a sensitivity of 86%, specificity of 82%, positive predictive value of 70%, and negative predictive value of 92% for metastatic melanoma.
PRAME is a useful marker for the diagnosis of melanoma in cytology material, but it is less sensitive than SOX10. PRAME is also expressed in other nonmelanocytic tumors which limits its specificity.
黑色素瘤优先表达抗原（PRAME）已被引入作为一种新的黑色素瘤标志物和免疫治疗的潜在靶点。虽然 PRAME 免疫组化（IHC）在外科病理学中已有充分的记录，但细胞学方面的类似数据有限。转移性黑色素瘤通常通过细胞学样本诊断，其中 IHC 发挥着重要作用。因此，我们旨在评估 PRAME IHC 在诊断细胞学样本中的转移性黑色素瘤方面的表现，与其他常用的黑色素瘤标志物进行比较。
该研究纳入了 156 例存档细胞学病例，其中 93 例为黑色素瘤病例，63 例为非黑色素瘤病例（对照组）。所有病例均在细胞块上进行 PRAME IHC 染色。使用定量和定性评分评估 PRAME 的核染色。还记录了其他黑素细胞 IHC 染色结果（SOX10、S-100、Melan-A 和 HMB45）。
在 86%的黑色素瘤病例中检测到肿瘤细胞中的 PRAME，明显低于 SOX10（100%）（p<.01），与 HMB45（84%）和 Melan-A（82%）相似。S-100 的敏感性最低，为 71%。与其他类型的黑色素瘤相比，梭形细胞黑色素瘤的 PRAME IHC 阴性率更高（4/10=40%）。PRAME 还在一些非黑素细胞性恶性肿瘤中表达，包括癌（5/22=23%）、肉瘤（5/15=33%）和血液恶性肿瘤（1/9=11%）。总的来说，PRAME 对转移性黑色素瘤的敏感性为 86%，特异性为 82%，阳性预测值为 70%，阴性预测值为 92%。
PRAME 是诊断细胞学标本中黑色素瘤的有用标志物，但敏感性不如 SOX10。PRAME 也在其他非黑素细胞性肿瘤中表达，这限制了其特异性。
