Tumorlike clusters of immature cells in cerebrospinal fluid of infants.

Cerebrospinal fluid (CSF) samples from four infants 3 days to 4 months of age with a history of prematurity or birth trauma were found to contain clusters of immature cells. These cells were arranged in groups or syncytia, sometimes with nuclear molding, and were cytologically characterized by scant basophilic cytoplasm, nuclei with fine nuclear chromatin, and small nucleoli. The picture simulated the appearance of metastatic tumor admixed with hemosiderin-laden macrophages, erythrocytes, and leukocytes. Because of the low numbers of cells or aggregates present in CSF samples and the relatively small quantity of CSF obtained, immunohistochemical and flow cytometric evaluations were not performed. Prior studies have designated these immature cells as undifferentiated leptomeningeal cells or cells from the subependymal germinal matrix and have associated their presence with intraventricular hemorrhage (IVH) in premature newborns. Three of our patients had a history of prematurity; the fourth patient suffered a traumatic birth but was not premature. In long-term follow-up, the patients have not shown progression of neurologic deficits or evidence of malignancy. Thus, it is important to recognize that in infants with a history of IVH, subarachnoid hemorrhage, or ventricular drainage devices, the presence of tumorlike clumps of cells associated with hemosiderin-laden macrophages most likely does not represent metastatic tumor.