Cerebrospinal fluid cytology studies of neuropsychiatric systemic lupus erythematosus

Background Neuropsychiatric systemic lupus erythematosus (NP-SLE) is the central nervous system (CNS) involvement of systemic lupus erythematosus (SLE). The diagnosis of NP-SLE may be difficult due to the lack of specific biomarker. CNS cerebrospinal fluid (CSF) cytology is diagnostic significant to CNS autoimmune disease. This paper described the characteristics of CSF cytology and evaluated its diagnostic value in NP-SLE. Methods Seventy-six eligible patients with clear diagnosis of NP-SLE were collected for CSF cytological examinations. Results The CSF cytology findings of 25 cases in 76 were abnormal, among which 16 cases showed lymphocytic inflammatory reactions; 8 cases had slight increase of neutrophile granulocyte percent; 9 cases showed lymphocyte-neutrophile inflammation. Activated lymphocytes together with monocytes were present in 24 cases. Among those cases, abnormal endocytosis of monocytes, which presented as monocytes phagocytosing lymphocytes or plasmocytes, was shown in 17 cases; plasmocytes were found in 17 cases. Conclusion The diagnosis of NP-SLE is based on clinical, neuroimaging and CSF studies. Among these methods, the CSF cytology findings are quite useful in practice, since the CSF cytological inflammatory reactions, especially the presentation of abnormal phagocytes in CSF is typical in NP-SLE and indicates its vasculitic mechanism.