The congenital presentation of Langerhans cell histiocytosis (LCH) is a rare presentation of an uncommon neoplastic process. Concurrent placental parenchymal involvement is even more rare, with just 2 cases of congenital multisystem LCH with placental involvement reported in English medical literature thus far. Here, we present a case of a liveborn male born at 37-weeks, 6-day gestation with congenital LCH focally involving the placenta. Langerhans cells were identified in an area of the placenta showing an unusual mononuclear cell infiltrate in the wall of the umbilical vein. Langerhans cells were also focally identified in areas of chronic villitis, as well as normal-appearing chorionic plate. The examination of the placenta in cases of clinical suspicion of LCH can be of paramount importance since it may provide the early diagnostic evidence of LCH. In this context, placental involvement by LCH should be considered even in the absence of abnormal histology.

中文翻译：

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先天性朗格汉斯细胞组织细胞增多症的胎盘：绒毛膜板和脐静脉异常受累的病例报告。

朗格汉斯细胞组织细胞增多症（LCH）的先天性表现是一种罕见的肿瘤过程的罕见表现。并发胎盘实质受累的情况更为罕见，迄今为止英文医学文献中仅报道了2例伴有胎盘受累的先天性多系统LCH。在此，我们介绍一例活产男性，出生于妊娠 37 周 6 天，患有局灶性累及胎盘的先天性 LCH。在胎盘的一个区域中发现了朗格汉斯细胞，显示脐静脉壁上有不寻常的单核细胞浸润。在慢性绒毛炎区域以及外观正常的绒毛膜板区域也发现了朗格汉斯细胞。在临床怀疑 LCH 的情况下，胎盘检查至关重要，因为它可以提供 LCH 的早期诊断证据。在这种情况下，即使没有异常组织学，也应考虑 LCH 累及胎盘。