A Neonatal Surprise: A Rare Round Ligament Cyst

Ligamentum teres (or round ligament) of the liver is a cord-like structure found within the falciform ligament. Lesions originating from the ligaments of the liver are a rare entity, especially in the pediatric population; they can be either benign or malignant. Here we report a case of a neonatal abdominal mass arising from the round ligament of the liver that was treated with surgical excision, raising the question of possible outcomes if left untreated. We present a case of a term female neonate born with an abdominal mass noticed after being investigated for feed intolerance; the mass was diagnosed with radiological imaging, surgically excised at the neonatal period, and sent for histopathology. It was found to be a benign cyst arising from the round ligament of the liver. Here we discuss the radiological and pathological findings of such a rare mass that, to the best of our knowledge, has not been found to be reported in the pediatric literature. Symptoms can be variable and nonspecific; the need for investigation and type of imaging with surgical vs. conservative intervention all depend on the nature of the mass or cyst arising from the liver ligaments; the final histopathology can be benign or malignant; therefore, excision is important to reach a final diagnosis. In conclusion, cysts of the round ligament of the liver in a neonate have yet to be described in the literature; the etiology and the possible future symptomatology, if left untreated, are still unknown.