Holmes Brittany J, Gown Allen M, Vang Russell, Ronnett Brigitte M, Yemelyanova Anna
Departments of Pathology (B.J.H., R.V., B.M.R., A.Y.) Gynecology and Obstetrics (R.V., B.M.R.), The Johns Hopkins University School of Medicine, Johns Hopkins Hospital, Baltimore, Maryland PhenoPath Laboratories (A.M.G), Seattle, Washington.
Int J Gynecol Pathol. 2014 Jul;33(4):425-31. doi: 10.1097/PGP.0b013e31829d7705.
PAX8 has emerged as a useful immunohistochemical marker for epithelial neoplasms of gynecologic origin. Expression of PAX8 in uterine malignant mesodermal mixed tumors (MMMT, carcinosarcoma) has not been characterized in detail. The goal of this study is to evaluate PAX8 expression in uterine MMMTs, with particular attention to its distribution in specific tumor components. Thirty-seven cases were studied. PAX8 expression was assessed by immunohistochemistry and scored separately in the epithelial and mesenchymal components of the tumors. The extent of staining was scored based on the estimated percentage of positive tumor cells as 1+: 1% to 25%; 2+: 26% to 50%; 3+: 51% to 75%; 4+: 76% to 100%. The epithelial component expressed PAX8 in all but 1 tumor, with 92% of tumors displaying 3+ and 4+ extent of staining. The mesenchymal component lacked PAX8 expression in 27 cases (73%) with variable expression in the remaining 10 cases. In addition, 12 tumors contained undifferentiated areas that were not readily classifiable as carcinoma or sarcoma based on morphologic features. Of these, 8 (67%) were negative for PAX8, whereas 4 (33%) demonstrated variable extent of expression. Thus, PAX8 is expressed in the carcinomatous components of nearly all uterine MMMTs (97%), with expression in sarcomatous and undifferentiated components being less common and less extensive. The uniform, extensive expression in the carcinomatous components makes PAX8 a useful marker for diagnosis of carcinomatous metastases of uterine MMMT at extrauterine sites. Its infrequent expression in the sarcomatous and undifferentiated components limits its utility in identifying sarcoma-predominant metastases as gynecologic in origin.
PAX8已成为一种用于妇科起源上皮性肿瘤的有用免疫组化标志物。PAX8在子宫恶性中胚叶混合瘤（MMMT，癌肉瘤）中的表达尚未得到详细描述。本研究的目的是评估PAX8在子宫MMMT中的表达，特别关注其在特定肿瘤成分中的分布。研究了37例病例。通过免疫组化评估PAX8表达，并分别对肿瘤的上皮和间叶成分进行评分。染色程度根据阳性肿瘤细胞的估计百分比进行评分：1+：1%至25%；2+：26%至50%；3+：51%至75%；4+：76%至100%。除1例肿瘤外，所有肿瘤的上皮成分均表达PAX8，92%的肿瘤显示3+和4+染色程度。间叶成分在27例（73%）中缺乏PAX8表达，其余10例表达各异。此外，12例肿瘤含有未分化区域，根据形态学特征难以归类为癌或肉瘤。其中，8例（67%）PAX8阴性，而4例（33%）表达程度各异。因此，PAX8在几乎所有子宫MMMT的癌性成分中均有表达（97%），而在肉瘤性和未分化成分中的表达较少且不广泛。癌性成分中一致、广泛的表达使PAX8成为诊断子宫MMMT宫外部位癌性转移的有用标志物。其在肉瘤性和未分化成分中罕见的表达限制了其在识别以肉瘤为主的妇科起源转移瘤中的应用。
