Subjects will be enrolled in sequential cohorts of NanoPac® at 6, 10, and 15 mg/mL at volumes equal to the amount of fluid aspirated from the cyst. Each cohort will have three subjects, with cohorts enrolled sequentially starting at the lowest concentration. Following Data Safety Monitoring Board (DSMB) review of the cohort data, the next cohort may begin enrolling, an additional three at the current dose may be enrolled, or if the first dose does not provide adequate safety and tolerability the study may be halted. The dose determined to be the most suitable for further evaluation, defined as the highest dose with an acceptable safety and tolerability profile (as determined by the DSMB), will enroll additional subjects to provide a total of 12 subjects at that dose level.