Divergent differentiation in gynecologic carcinomas encompasses a broad range of lineages, including mesenchymal, germ cell, high-grade neuroendocrine, neuroectodermal, and cutaneous adnexal differentiation. Here we present a case of ovarian endometrioid adenocarcinoma with divergent malignant melanocytic differentiation (MMeD). The background ovarian endometrioid adenocarcinoma showed focally aberrant β-catenin expression and histologic patterns associated with β-catenin activation, including spindled elements and corded and hyalinized foci. The areas with MMeD had both spindled and epithelioid morphology, diffusely aberrant β-catenin expression, expression of melanocytic markers (an HMB45/Mart-1 cocktail, MITF, and S100), and no staining for myogenic markers (SMA and desmin) or epithelial markers (cytokeratins and E-cadherin). INI1, BRG1, PMS2, and MSH6 were retained, and p53 showed a wild-type expression pattern. No areas with definitive carcinosarcomatous differentiation were identified despite extensive sampling. While a single case of gynecologic carcinosarcoma with a serous epithelial component and a small focus on malignant melanoma has been reported in the English literature, the current case represents what is, to the best of our knowledge, the first case of MMeD arising in the context of a β-catenin activated endometrioid adenocarcinoma. Pathogenetic and differential diagnostic considerations are discussed.

中文翻译：

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β-连环蛋白表达异常的卵巢子宫内膜样腺癌中不同的恶性黑素细胞分化：扩大 β-连环蛋白激活的妇科肿瘤组织学谱的病例。

妇科癌的分化分化涵盖广泛的谱系，包括间充质分化、生殖细胞分化、高级神经内分泌分化、神经外胚层分化和皮肤附件分化。在这里，我们介绍一例卵巢子宫内膜样腺癌，伴有不同程度的恶性黑素细胞分化（MMeD）。背景卵巢子宫内膜样腺癌显示局灶性异常的β-连环蛋白表达和与β-连环蛋白激活相关的组织学模式，包括梭形元件和绳状和透明样变灶。患有 MMeD 的区域具有梭形和上皮样形态，广泛异常的 β-连环蛋白表达，黑色素细胞标记物（HMB45/Mart-1 混合物、MITF 和 S100）的表达，并且没有肌源性标记物（SMA 和结蛋白）或上皮细胞的染色。标记物（细胞角蛋白和 E-钙粘蛋白）。INI1、BRG1、PMS2 和 MSH6 被保留，p53 显示野生型表达模式。尽管进行了大量采样，但没有发现具有明确癌肉瘤分化的区域。虽然英文文献中报道了一例具有浆液性上皮成分且少量关注恶性黑色素瘤的妇科癌肉瘤病例，但据我们所知，当前病例代表了在此情况下出现的第一例 MMeD 病例β-连环蛋白激活的子宫内膜样腺癌。讨论了发病机制和鉴别诊断的考虑因素。