Neuropathology of "septo-optic dysplasia" (de Morsier syndrome) with immunohistochemical studies of the hypothalamus and pituitary gland.

The de Morsier syndrome, or septo-optic dysplasia, is a developmental anomaly characterized by involvement of the optic system, hypothalamic-pituitary axis and septum pellucidum. Only a few anatomical observations are recorded. We report three new cases and review the pertinent literature. The neuropathological lesions varied as did the clinical features. The hypothalamic nuclei were most commonly involved, followed by the optic system and the septum pellucidum. Other lesions were found in the cerebral cortex, corpus callosum, olfactory system and cerebellum. The hypopituitarism appeared to have been secondary to hypothalamic damage rather than to intrinsic pituitary defect. A virtually normal histology and the usual endocrine cell populations were demonstrated by immunocytochemistry in the adenohypophysis. Damage to the neurophysin-containing cells of the hypothalamus explains the various degrees of clinically observed diabetes insipidus.