Histiocytosis X: abnormal cerebrospinal fluid cytology in extrahypothalamic central nervous system involvement.

The clinical course and long-term survival of a patient with acute disseminated histiocytosis X and extrahypothalamic CNS involement were presented. The clinical significance of histiocytes appearing in the CSF cocomitant with the onset of this neurologic syndrome was discussed. Detailed cytologic examination of the CSF in patients with histiocytosis X and CNS involvement was recommended.