Cyst fluid analysis for tumor markers (carcinoembryonic antigen: CEA, CA 125), relative viscosity and cytology can credibly distinguish malignant cystic tumors and potentially premalignant mucinous cystic neoplasms from pseudocysts and serous cystadenomas, amylase content with isoenzyme analysis is useful to identify pseudocysts [17]. The gene discussed is CEACAM5; the disease is serous cystadenoma.