A case of isolated langerhans cell histiocytosis of the hypothalamus with remission and regrowth after surgery.

We describe a new case of isolated Langerhans cell histiocytosis (LCH) of the hypothalamus. A 53-year-old female patient presented with polydipsia, headache, anorexia, and fatigue. Neurological imaging revealed a mass projecting from the hypothalamus into the third ventricle. Gross total removal of the tumor was performed. Light microscopy showed LCH, and immunohistochemical studies revealed S-100 and CD1a immunoreactivity in the Langerhans cells. Although the most common CNS site for LCH is the hypothalamus, isolated hypothalamic LCH, confirmed by biopsy, is very rare. The residual mass appeared to remit spontaneously 3.5 years after surgery, with regrowth 3 years later.