Mucinous cystadenoma (lat. cystadenoma mucinosum - cyst with mucous membrane, cystadenoma mucous cyst), also known as cystadenoma pseudocyst or cystadeninchodenoma. Cystadenomycosis can form in the ovaries, cervix, mammary glands and kidneys. When this formation develops in the kidneys, it is also known as the benign cystic form of renal epithelial tumor. A mucous benign pseudocyst is not a malignant formation and does not pose a threat to the patient’s life. It can be observed in both women and men. The age of patients is not limited. Cystaden pseudocyst also occurs in children. It's rare, but it still happens. Benign ovarian cysts in little girls can appear as early as 8-12 years of age.