Find out about COVID-19, COVID-19 vaccines, and Mayo Clinic patient and visitor updates.
Featured conditions Brain tumor, breast cancer, colon cancer, congenital heart disease, heart arrhythmia. See more conditions.
Featured conditions
During a molar pregnancy, the placental tissue develops abnormally, and can appear as a mass of cysts. The embryo either doesn't form or is malformed and can't survive.
Mayo Clinic does not endorse companies or products. Advertising revenue supports our not-for-profit mission.
Check out these best-sellers and special offers on books and newsletters from Mayo Clinic Press.