Agenesis of the thyroid isthmus was observed in an adult male cadaver during a routine dissection at the anatomy laboratory of the Faculty of Medicine and Odontostomatology (FMOS) in Bamako. The two thyroid lobes were completely separated from each other. The left lobe presented the pyramidal lobe. The supra and infra-isthmic arches were absent, the upper right and left thyroid arteries did not anastomose, as did the lower right and left thyroid arteries. On the right side, the superior laryngeal and crico-thyroid arteries were born by a common trunk which came from the external carotid artery by a common trunk with the lingual and superior thyroid arteries.
