Tumor induction by Cryptococcus neoformans.

A human isolate of Cryptococcus neoformans strain CIA, which was originally obtained in 1963, produced fatal disease in mice. Postmortem examinations showed extensive central nervous system disease. After using this yeast for research for 7 years, we found that it began to produce large tumors after intraperitoneal inoculation in mice. The present study showed that the tumors consisted of large agglomerates of yeast cells, capillaries, and reticular stroma. In concomitant experiments, the same C. neoformans strain, introduced into the lungs of mice in an aerosol, produced asymptomatic infections. A definition for the term "cryptococcoma" is proposed.