P08.04 * LEPTOMENINGEAL CARCINOMATOSIS VS LEPTOMENINGEAL LYMPHOMATOSIS: COMPARISON OF THE CEREBROSPINAL FLUID INFLAMMATORY CELLS
Authors: D. Subira, M. Simo, J. Illan, S. Castanon, R. Gonzalo, M. Martinez-Garcia, J. Pardo, L. Gomez, M. Navarro, J. Bruna
Journal: Neuro-Oncology (2014)

BACKGROUND: The inflammatory-cell infiltrate surrounding solid tumours is progressively gaining importance, in an attempt to reach a better understanding of the pathophysiology of the disease, and also improve future design of immune-based cancer therapies. However, information about the inflammatory cell populations in leptomeningeal disease is scarce. STUDY DESIGN: We have studied the distribution of the main inflammatory cell populations in the cerebrospinal fluid (CSF) from 83 patients diagnosed with leptomeningeal carcinomatosis (LC, n = 65) and lymphomatosis (LyM, n = 18). These samples were matched with CSF samples from another set of patients diagnosed with similar epithelial-cell carcinomas (n = 36), and diffuse B-cell high-grade lymphoma (n = 19), but without leptomeningeal involvement. Patients with infectious or inflammatory diseases were excluded from this study. Diagnosis of leptomeningeal disease was established on the basis of clinical symptoms, CSF cytology, magnetic resonance images and/or CSF biochemical data. METHODS: Flow cytometry immunophenotyping (FCI) was used to describe the percentage of lymphocytes, monocytes and polymorphonuclear cells (PMN) in the CSF samples on the basis of their forward and side-scatter characteristics. Only CSF samples without red-cell contamination entered the study. RESULTS: No differences in the distribution by sex, age, volume of CSF sample received, absolute CSF cell-count, and levels of CSF glucose and protein was found between patients with LC and LyM. Median (interquartile) CSF inflammatory cells/mm3 was 7.96 (2.5-17.6) in LC, and 2.71 (1.2-6.9) in LyM (p = 0.043). Median (interquartile) rates of lymphocytes, monocytes and PMN cells were 59.7% (35-76.6), 24% (16-53) and 1.5% (0-7.6) in LC, and 98.5% (70.8-100), 1.5% (0-29.3), and 0% in LyM (p < 0.001). No difference was observed between patients with breast (n = 30) and lung adenocarcinoma (n = 21). Also, no statistical difference was found in the relative distribution of each leukocyte population after comparison of CSF samples with or without a positive detection of malignant cells, using either cytology or FCI. All patients with lymphoma (with and without LyM) had a similar CSF leukocyte distribution. In contrast, the absolute number of lymphocytes and monocytes showed significant differences between patients with LC and patients with cancer without LC (p<0.001). Interestingly, PMN cells were only detected in cases with LC (>1% PMN in 38/65 samples; p= 0.002). CONCLUSIONS: A different inflammatory cell background was seen in the CSF from patients with LyM and LC. CSF samples from patients with LC had a higher number of inflammatory cells and a recurrent description of PMN cells, a distinctive parameter not found in patients with LyM and cancer patients without LC. Further studies are warranted to determine the significance of these exploratory findings.