Changing Course of an Umbilical Cord Mass - Chasing the Diagnosis of Angiomyxoma

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.