Cerebrospinal fluid cytology: an 11-year experience with 5951 specimens

Cerebrospinal fluid (CSF) diagnoses encompass a wide spectrum of conditions. The authors review one institution's CSF cytology results over an 11-year period.

A retrospective study of 5951 CSF specimens generated between 1985 and 1995. Specimens from pediatric patients (<19 years of age) from the same time period were separately identified.

A total of 5561 adult and 390 pediatric CSF specimens were interpreted. A diagnosis of "negative for malignant cells" was assigned in 5171 (93%) of the adult cases and in 351 (90%) of the pediatric cases. Specific infectious organisms were identified in 26 adult specimens and one pediatric specimen. Cryptococcus was the most common infectious agent observed (n = 23 adults), and Toxoplasma was the sole pediatric infectious agent. Two hundred seventy-six (5%) adult cases and 31 (8%) pediatric cases were positive for malignant cells. Diagnoses included metastatic tumors (adult, 140 [51%]; pediatric, 0); lymphoma/leukemia (adult, 112 [41%]; pediatric, 4 [13%]); malignant unclassified neoplasms (adult, 9 [3%]; pediatric, 0); and primary central nervous system neoplasms (adult, 12 [4%]; pediatric, 27 [87%]). Medulloblastoma was the most common pediatric neoplasm (n = 21). There were 105 (2%) adult cases and 8 (2%) pediatric cases with atypical cells present. Atypical lymphoid cells were the most common type in adult cases (53%).

In our experience, infectious agents were rarely identified in pediatric CSF specimens. In adult specimens, the most commonly identified organisms was Cryptococcus. Primary central nervous system neoplasms accounted for a higher percentage of CSF specimens in the pediatric population than in the adult population. The most commonly identified malignancy in adults was metastatic neoplasms, and in children, medulloblastoma.