The literature indicates that mesonephric carcinoma (MC) and mesonephric-like adenocarcinoma (MLA) typically lack mucinous and squamous features/differentiation. We report 4 cases of ovarian mucinous tumors (1 mucinous cystadenofibroma and 3 mucinous borderline tumors/atypical proliferative mucinous tumors [MBT/APMT]) co-existing with mesonephric-like lesions which were highlighted by Gata3 and Pax8 expression. All cases contained benign mesonephric-like proliferations (MLP) which focally displayed gastrointestinal-type mucinous metaplasia/differentiation and some were intimately admixed with mucinous glands associated with the mucinous tumor. Metaplastic mucinous epithelium retained expression of Gata3 and Pax8 in some areas while 1 mucinous cystadenofibroma and 1 MBT/APMT were focally positive for Pax8. Along with these mesonephric components, case 1 exhibited features of mesonephric hyperplasia and in 2 cases, 3 and 4, MLA was identified. In case 4, aKRASc.35G>T (p.Gly12Val) somatic mutation was detected in both the MBT/APMT and the MLA, indicating a clonal origin. This same mutation was also detected in the benign MLP, indicating that it was likely an early genetic event. ACTNNB1c.98C>T (p.Ser33Phe) somatic mutation,FGFR2amplification, andCDKN2A/p16deletion were only detected in the MLA but not in the MBT/APMT. Our result provides evidence to demonstrate the clonal relationship between these morphologically distinct components. Although speculative, we postulate that benign MLPs may give rise to lineage-specific mucinous and mesonephric-like lesions and propose that the MLPs are a new possible origin of some ovarian mucinous tumors. Whether these MLPs arise through transdifferentiation of Müllerian tissue or represent true mesonephric remnants, however, remains largely unknown.

文献表明，中肾癌（MC）和中肾样腺癌（MLA）通常缺乏粘液和鳞状特征/分化。我们报告了 4 例卵巢粘液性肿瘤（1 例粘液性囊腺纤维瘤和 3 例粘液性交界性肿瘤/非典型增殖性粘液性肿瘤 [MBT/APMT]）与中肾样病变共存，其中 Gata3 和 Pax8 表达突出。所有病例均含有良性中肾样增生（MLP），局部表现为胃肠道型粘液化生/分化，有些与粘液肿瘤相关的粘液腺紧密混合。化生性粘液上皮在某些区域保留了 Gata3 和 Pax8 的表达，而 1 例粘液性囊腺纤维瘤和 1 例 MBT/APMT 的 Pax8 局灶性阳性。除了这些中肾成分外，病例 1 还表现出中肾增生的特征，而在 2 例（3 号和 4 号）中，还发现了 MLA。在病例 4 中，MBT/APMT 和 MLA 中均检测到KRAS c.35G>T (p.Gly12Val) 体细胞突变，表明克隆起源。在良性 MLP 中也检测到了相同的突变，表明这可能是早期遗传事件。仅在 MLA 中检测到 CTNNB1 c.98C>T (p.Ser33Phe) 体细胞突变、FGFR2 扩增和 CDKN2A/p16 缺失，而在 MBT/ APMT中未检测到。我们的结果提供了证据来证明这些形态上不同的成分之间的克隆关系。尽管是推测，但我们假设良性 MLP 可能会引起谱系特异性粘液性和中肾样病变，并提出 MLP 是某些卵巢粘液性肿瘤的新可能起源。然而，这些 MLP 是否是通过苗勒管组织的转分化产生的，还是代表真正的中肾残余物，目前仍不清楚。