Rare anatomical variation: analysis of an aberrant right subclavian artery in three cadavers

An aberrant right subclavian artery (ARSA) is a congenital vascular anomaly in which the right subclavian artery originates directly from the aortic arch distal to the left subclavian artery. Although often asymptomatic, ARSA can lead to clinical complications, such as dysphagia, upper respiratory issues, and vascular events. In this study, we examined the gross anatomical and histological characteristics of the ARSA based on three cadavers selected from a total of 7 ARSA cases identified among 3,158 specimens dissected between 1948 and 2024 at Nihon University School of Medicine (overall incidence: 0.22%). All three cases exhibited a retroesophageal course of the ARSA and absence of the right recurrent laryngeal nerve, replaced by a non-recurrent laryngeal nerve. One case also presented a bicarotid trunk. Histological analysis of one cadaver revealed variable patterns of intimal thickening in the ARSA, particularly at the flattened segment compressed between the esophagus and vertebral body, suggesting localized hemodynamic stress. Despite these structural changes, the tunica media remained intact. No Kommerell diverticulum was observed. These findings highlight the embryological and structural basis of ARSA and its potential clinical relevance in surgical and endovascular procedures. The presence of ARSA should prompt careful preoperative planning to avoid nerve injury or procedural complications. The observed correlation between arterial flattening and histological changes may also help explain some embolic phenomena previously reported in patients with ARSA. This study contributes new insights into the anatomical variations and histopathological features of ARSA, with particular relevance to vascular and head and neck surgery.