The cytodiagnosis of meningeal involvement in familial haemophagocytic lymphohistiocytosis.

The cytological appearances of the cerebrospinal fluid (CSF) in two cases of familial haemophagocytic lymphohistiocytosis (FHL) are described. The presence of numerous lymphocytes and immature macrophages in the CSF, some of which showed lymphohistiocytosis, was indicative of meningeal involvement. The appearance of large numbers of immature macrophages indicated rapid deterioration and death within a few weeks. Furthermore, some CSF samples taken at times when the patients were asymptomatic contained suspicious cells, indicating asymptomatic persistence of the meningeal lesions. Thus, cytological examination of CSF can assist with the management of patients with this rare disease.