Coulter counter identifies Cryptococcus neoformans as leukocytes. A case of pseudopleocytosis.

Cerebrospinal fluid from a 42-year-old man with acquired immune deficiency syndrome was processed in a Coulter S-plus counter and found to contain "4.8 x 10(9) leukocytes/L:56.1% granulocytes and 37.7% lymphocytes." Direct examination of the same specimen in a counting chamber revealed that the leukocytes were cells of Cryptococcus neoformans. Coulter analysis of cerebrospinal fluid may be inappropriate, particularly when yeast infection is a probable diagnosis.