• hypothalamus
• amnesia
• Langerhans cell

Langerhans cell histiocytosis (LCH), a rare disease previously known as histiocytosis X, is characterised by abnormal cell proliferation. If the CNS is invaded, the hypothalamus is the typical site location. There are virtually no neuropsychological data on hypothalamic LCH sequelae. Memory disorders in the context of posterior but also anterior hypothalamic lesions, regardless of the aetiology, have in most cases been attributed to the involvement of the mammillary bodies (MB). However, Ptak et al reinterpreted a case, acknowledging that “Damage of the anterior hypothalamus, rather than the mammillary bodies, may [ . . .] have been responsible for [the observed] confabulatory amnesia” (page1600).¹ An interesting question is whether neuropsychological deficits are secondary to hypothalamic damage in itself or to a disconnection syndrome. The latter is based on the bilateral hypothalamic nucleus—widespread brain complex connections. Two subsystems are of particular interest in the present case, the hippocampus-fornix-hypothalamus-MB circuit, and the amygdala-stria terminalis plus caudate nucleus-hypothalamus circuit.

We report the case of a patient who presented with hypothalamic LCH and underwent thorough neuropsychological, radiological, …