The spectrum of malignant diagnoses in cerebrospinal fluid cytology from an adult population: a multi-institutional retrospective review.

Introduction: Limited updated literature exists about the prevalence and spectrum of malignancies involving cerebrospinal fluid (CSF). In this multi-institutional study, we review our experience with focus on first time malignancy diagnosis in CSF samples of adults.
Materials and Methods: Institutional databases at 4 academic centers were queried retrospectively for CSFs over a 10-year period. The following data elements were collected: total # of CSFs, total # of CSFs with a malignant diagnosis; for each patient with a first time CSF diagnosis of malignancy: age, gender, diagnosis, prior history of malignancy, and ancillary studies.
Results: Twenty-four thousand one hundred forty-two CSFs were collected with a positive for malignancy rate of 2.3% (n = 551). Out of 347 (1.4%) adults with a first-time diagnosis of CSF malignancy 182 (52%) were female (age range: 19-89/mean: 57) and 165 (48%) were male (age range: 20-95/mean: 60). Hematolymphoid malignancies (48%, n = 168) were overall the most common neoplasm. In women, metastatic carcinomas (63%, n = 114) were the leading malignancy, of which the majority were breast primaries. In men, lymphomas/leukemias (64%, n = 106) were the leading malignancy, of which the majority were B-cell lymphomas. Ancillary studies aided the final diagnosis in 110 (32%) cases. For 286 (82%) cases, a prior history of malignancy was available to correlate CSF findings.
Conclusions: A malignancy diagnosis in the CSF of adults is rare. The most common malignancies in females and males are metastatic breast carcinoma and hematolymphoid malignancies, respectively. Metastatic neoplasms account for the majority, with primary central nervous system neoplasms being quite uncommon. History of malignancy and ancillary tests can be helpful.
(Copyright © 2023 American Society of Cytopathology. Published by Elsevier Inc. All rights reserved.)