Cytopathologic presentation of cerebral histiocytosis.

Histiocytoses involving the central nervous system are rare, and those in which the brain and meninges are the the only systems affected are rarer still. This paper presents such a case, in which cytologic study of cerebrospinal fluid during life showed large numbers of abnormal histiocytes and necropsy showed infiltration of brain and meninges by masses of similar cells, without other systems being involved. The cytologic features and differential diagnosis are discussed.