多脾臓から無脾臓へ：異位症候群の2例からの洞察

Heterotaxy syndrome is a rare congenital disorder characterized by abnormal arrangement of the thoracic and abdominal organs and is classified into polysplenia (left isomerism) and asplenia (right isomerism) syndromes. Polysplenia is associated with multiple splenic nodules, bilobed lungs, vascular anomalies, and organ malpositioning. In contrast, asplenia features bilateral trilobed lungs and eparterial bronchi, and is commonly associated with severe cardiac defects and high neonatal mortality. Here, we report 2 cases that illustrate the clinical spectrum of heterotaxy syndrome. The first case involved a 59-year-old female presenting with vague abdominal pain that was incidentally found to have features of polysplenia syndrome, including multiple splenules, malpositioned liver, partial pancreatic agenesis, and bilobed lungs. The second case was a 26-hour-old neonate who presented with cyanosis and respiratory distress and was diagnosed with right isomerism and complex congenital heart disease, including right ventricular outflow tract (RVOT) stenosis, atrioventricular canal defect, situs inversus, and asplenia. These cases highlight the varied presentations and anatomical complexity of heterotaxy syndrome, emphasizing the role of imaging in its diagnosis and clinical management.