Atypical course of the azygos vein and its tributaries: a case report.

During routine cadaveric dissection of an 88-year-old man, an atypical course of the azygos vein was found. The azygos vein was formed by the subcostal and lumbar veins at the level of the eleventh vertebra and to the left of the midline. Initially ascending on the left side, the vein gradually shifted to the right at approximately T8 level, eventually draining into the superior vena cava. The large venous vessel, measuring up to 9 mm in diameter, served as the sole independent outlet for bilateral posterior intercostal veins from the fourth to the eleventh intercostal spaces. An atypical course and morphological variations of venous structures is clinically significant, especially for radiologists and thoracic surgeons, to avoid confusion with with aneurysms, tumours, or lymphadenopathies and improve perioperative outcomes.