We detected in the cystic fluid of all tumors some proteins that are already known to play a role in one or more of the cystic tumors studied: gelsolin (GSN), haptoglobin (HP), alpha-2-HS-glycoprotein (AHSG) and alpha-1-antichymotripsin (AACT). The gene discussed is GSN; the disease is cystic neoplasm.