Congenital Agenesis of the Olfactory Bulbs: What to Suspect?

Complete agenesis of the olfactory bulbs (OB) constitutes a rare cause of congenital anosmia, which is more often associated with cerebral malformations or genetic disorders. The authors present a very rare case of a 28-year-old caucasian male with complaints of complete lack of the sense of smell since childhood. Radiologic study confirmed complete bilateral agenesis of the OB, with no other radiologic or clinical findings, such as delayed sexual development. Laboratorial investigation confirmed no signs of adrenocortical insufficiency. Despite being immature in the term neonate, the OB are already functional at birth. Congenital agenesis of the OB can occur as an isolated deformity. On the other hand, it is a constant feature of several genetic syndromes, such as Kallmann's syndrome or alobar holoprosencephaly. Most cases of isolated congenital anosmia occur sporadically, with no family history of the condition. Given the fact that no curative treatment is available, counselling for daily living precautions should be given to all patients. This is one of the first case reports about complete and isolated agenesia of the OB diagnosed in adulthood. The authors highlight the need to exclude several genetic syndromes that may be associated, albeit in a dissimulated way.