Angiomyxoma of the umbilical cord is a rare benign vascular malformation with potential for fetal morbidity and mortality. Gross and histologic features of this lesion are identical to those described as “hemangioma,” however “angiomyxoma” is a preferable term as current practice restricts the term “hemangioma” to infantile capillary proliferations that express glucose transporter 1. Here we describe the case of an umbilical cord angiomyxoma with associated pseudocysts diagnosed after delivery at 33 weeks. It presented as a heterogeneous-appearing mass near the fetal cord insertion and mimicked serious fetal anomalies throughout gestation. We found fetal MRI helpful for monitoring this lesion, narrowing the differential, and informing management. Proximity to the fetal end of the cord and uncertainty about diagnosis also required surgical resection of the mass after delivery with umbilicoplasty.

脐带血管粘液瘤是一种罕见的良性血管畸形，具有潜在的胎儿发病率和死亡率。这种病变的大体和组织学特征与描述为“血管瘤”的相同，但是“血管粘液瘤”是一个更可取的术语，因为目前的实践将“血管瘤”这一术语限制为表达葡萄糖转运蛋白 1 的婴儿毛细血管增生。这里我们描述了这种情况产后 33 周诊断为脐带血管粘液瘤伴假性囊肿。它在胎儿脐带插入附近表现为异质性肿块，并在整个妊娠期间模仿严重的胎儿异常。我们发现胎儿 MRI 有助于监测这种病变、缩小鉴别范围并为管理提供信息。