Accessory mammillary bodies formed by the enlarged lateral mammillary nuclei: cytoarchitecture.

Post mortem examination of the hypothalamus of a 79-year-old woman, deceased in cardiac arrest without recorded neurological symptoms, revealed well-defined spherical protrusions located rostro-laterally to the mammillary bodies that appear to be regular size when compared to normal. Cytoarchitectonically, these accessory mammillary bodies are formed by the enlarged lateral mammillary nucleus that is normally a thin shell over the medial. The mammillary nuclei appear to function synergistically in memory formation in rats; however, the functional consequences of the present variation are difficult to interpret due to lack of human data. Most importantly, in addition to the possible functional consequences, lateral mammillary bodies can be falsely identified as various neuropathological processes of the basal diencephalon including gliomas; therefore, it is extremely important to disseminate this unique morphological variant among clinicians.