Discovery and management of accessory hemidiaphragm during video-assisted thoracoscopic segmentectomy for pulmonary nodule: a case report.

An accessory hemidiaphragm is a rare congenital intrathoracic malformation characterized by a fibromuscular diaphragm located superior to the normal diaphragm, typically featuring a central hiatus through which pulmonary vessels and bronchi traverse. This anomaly is often associated with scimitar syndrome. We present a unique case of an isolated accessory hemidiaphragm-devoid of the characteristic vascular anomalies typical of scimitar syndrome-discovered incidentally during thoracoscopic surgery performed for a pulmonary nodule. This report elaborates the rationale for performing a concurrent partial membranectomy and underscores the necessity of an individualized surgical strategy in such cases.