Intrathoracic accessory liver tissue and cleidodysplasia in a newborn: a rare case report and literature review

Intrathoracic accessory liver tissue (IALT) is a rare congenital anomaly that can cause life-threatening respiratory compromise in neonates due to mass effect, yet its association with other skeletal dysplasias remains unexplored. We report the first known case of a neonate presenting with severe respiratory failure caused by a large IALT, concurrently diagnosed with congenital right-sided cleidodysplasia. Preoperative three-dimensional (3D) computed tomography (CT) reconstruction was pivotal in visualizing the vascular pedicle connecting the ectopic tissue to the main liver, effectively differentiating IALT from congenital diaphragmatic hernia (CDH), congenital pulmonary airway malformation (CPAM), and hepatic-pulmonary fusion. Importantly, we propose a novel volumetric ratio—comparing the IALT tissue volume to the right thoracic cavity capacity—to quantitatively assess its impact on respiratory function. Following stabilization with invasive mechanical ventilation, the patient underwent successful video-assisted thoracoscopic surgery (VATS), which required meticulous dissection of the feeding artery and draining vein while navigating the technical challenges of one-lung ventilation in a neonate. Postoperative histopathology confirmed Type II IALT, and whole-exome sequencing (WES) identified a heterozygous variant in the UGT1A1 gene; however, the pathogenic link between this metabolic gene, IALT, and cleidodysplasia remains unelucidated, suggesting a potential novel syndromic association. This case highlights the critical diagnostic value of 3D CT reconstruction in distinguishing IALT from other thoracic masses and demonstrates the feasibility of VATS for neonatal resection despite technical complexities. The unprecedented co-occurrence of IALT and cleidodysplasia expands the phenotypic spectrum of congenital anomalies, warranting further genetic investigation and rigorous long-term follow-up given the theoretical risk of malignant transformation observed in other ectopic liver tissues. Furthermore, we reviewed and synthesized current literature on pediatric IALT to further clarify its clinical characteristics and the current status of diagnosis and treatment.