背景:黑色素瘤中优先表达的抗原(PRAME)免疫染色在确认黑素细胞病变的恶性方面具有重要的诊断用途。然而,PRAME在生殖器黑素细胞病变中的表达尚未见报道。在这项研究中,对一组生殖器黑素细胞病变进行PRAME染色,目的探讨PRAME在生殖器黑素细胞病变中的诊断作用及其在不典型生殖器痣中的表达。
方法:包括生殖器侵袭性黑色素瘤在内的队列,原位黑色素瘤,非典型生殖器痣(AGN),复合痣,皮内痣,蓝色痣,通过组织学回顾和PRAME免疫染色来检索扁桃体和黑变病。
结果:共66例。PRAME在侵袭性黑色素瘤和原位黑色素瘤中的平均表达比例分别为56.75%和57.43%,平均H分数分别为153.5/300和163.14/300,高于AGN(3.25%,7.75/300,p<0.001),复合/皮内痣,扁豆/黑变病,和背景交界黑素细胞(<1%,<1/300,p<0.001)。PRAME表达的不同截止,敏感性和特异性分别为65.22%和100%(>100/300);69.57%和95.83%(>10/300);82.61%和93.75%(≥1/300)。在一半的AGN病例中看到低水平的PRAME表达(n=2/4,50%),并且在低截止值(>10/300和≥1/300)下无法区分侵袭性黑色素瘤和AGN(p>0.05)。
结论:对于生殖器黑色素细胞病变,PRAME免疫染色在强和扩散染色时显示出高特异性。AGN并不罕见地显示低水平表达。PRAME局灶性和/或弱表达不应被视为恶性肿瘤的绝对指征。全面的组织学评估仍然是准确诊断黑素细胞病变的关键。
BACKGROUND: The Preferentially Expressed Antigen in Melanoma (PRAME) immunostain has seen significant diagnostic use in confirming malignancy for melanocytic lesions. However, the expression of PRAME in genital melanocytic lesions have not been reported. In this study, PRAME staining was performed on a cohort of genital melanocytic lesions, aiming to investigate the diagnostic role of PRAME in genital melanocytic lesions and its expression in atypical genital nevi.
METHODS: A cohort including genital invasive melanoma, melanoma-in-situ, atypical genital nevus (AGN), compound nevus, intradermal nevus, blue nevus, lentigo and melanosis was retrieved with histology reviewed and PRAME immunostaining performed.
RESULTS: A total of 66 cases were reviewed. The average proportion expression of PRAME were 56.75 % and 57.43 % for invasive melanoma and melanoma-in-situ, with average H-scores of 153.5/300 and 163.14/300 respectively, which were greater than AGN (3.25 %, 7.75/300, p<0.001), compound/intradermal nevi, lentigo/melanosis, and background junctional melanocytes (<1 %, <1/300, p<0.001). The different cutoffs of PRAME expression, the sensitivity and specificity were 65.22 % and 100 % (>100/300); 69.57 % and 95.83 % (>10/300); and 82.61 % and 93.75 % (≥1/300) respectively. Low level PRAME expression was seen in half of the cases of AGN (n=2/4, 50 %), and at low cutoffs (>10/300 and ≥1/300) unable to differentiate invasive melanoma from AGN (p>0.05).
CONCLUSIONS: For genital melanocytic lesions, PRAME immunostain shows high specificity at strong and diffuse staining. AGN not uncommonly display low level expression. Focal and/or weak PRAME expression should not be considered as an absolute indication of malignancy, and comprehensive histological assessment remains the key to accurate diagnosis of melanocytic lesions.