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Tumor vs. cyst: What's the difference?
By Mayo Clinic staffOriginal Article: http://www.mayoclinic.com/health/tumor/AN00463

- With Mayo Clinic medical oncologist
Timothy J. Moynihan, M.D.
read biographyclose windowBiography of
Timothy J. Moynihan, M.D.
Timothy Moynihan, M.D.
"As a practicing medical oncologist, I meet with patients and families every day to help manage their course through this disease called cancer. This experience provides unique insight into the needs of cancer patients, their families and loved ones and brings into sharp focus the need for reliable information to be readily available in terms that can be easily understood." — Dr. Timothy Moynihan
Dr. Timothy Moynihan believes that providing consumers with accurate, timely information on the broad, complex topic of cancer is the biggest challenge facing medical websites. As the guiding force behind our cancer content, he makes sure Mayo Clinic meets the test.
Dr. Moynihan, born in Las Vegas, N.M., and raised in Denver, is a consultant in medical oncology at Mayo Clinic and an associate professor at Mayo Clinic College of Medicine, Rochester, Minn. He's board certified in internal medicine, medical oncology, and hospice and palliative care medicine.
He did his medical oncology training at Johns Hopkins Hospital in Baltimore, and then went on to the University of Minnesota and St. Paul Regions Medical Center for seven years before moving to Mayo Clinic in 1999. Dr. Moynihan is medical director of the Mayo Clinic hospice.
Dr. Moynihan serves as the education chair for the Department of Oncology and the fellowship program director. Four times he has been selected as Teacher of the Year in medical oncology and elected to the Teacher of the Year Hall of Fame.
Past honors include distinguished clinical teacher at the University of Minnesota Medical School, best internist at the Medical College of Wisconsin and recipient of the Upjohn Achievement Award for Excellence in Medicine. Dr. Moynihan serves on several national committees for the American Society of Clinical Oncology.
"The Internet provides a ready source of information on a wide range of topics of interest to those affected by cancer," Dr. Moynihan says. "The difficulty is trying to decide which sites provide reputable information and which information is relevant to each individual patient. The long history and tradition of excellence associated with Mayo Clinic assures you that information provided will be reliable, up-to-date and comprehensive."
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Question
Tumor vs. cyst: What's the difference?
What's the difference between a tumor and a cyst? Could a cyst be cancerous?
Answer
from Timothy J. Moynihan, M.D.
Tumors and cysts are two distinct entities.
- Cyst. A cyst is a sac that may be filled with air, fluid or other material. A cyst can form in any part of the body, including bones, organs and soft tissues. Most cysts are noncancerous (benign). Some common examples of cysts include sebaceous cysts, small bumps that form just beneath the skin, and ovarian cysts. It's important to note, however, that nearly all cancers are capable of producing cysts.
- Tumor. A tumor is an abnormal mass of tissue. Like a cyst, a tumor can form in any part of the body. A tumor can be benign or cancerous (malignant).
To determine whether a cyst or tumor is benign or malignant, a sample of the affected tissue — or, in some cases, the entire suspicious area — is removed and studied under a microscope. This is known as a biopsy.
Next questionSmall cell, large cell cancer: What this means
- Dictionary of cancer terms: C. National Cancer Institute. http://www.cancer.gov/templates/db_alpha.aspx?expand=C. Accessed Dec. 29, 2010.
- Dictionary of cancer terms: T. National Cancer Institute. http://www.cancer.gov/templates/db_alpha.aspx?expand=T. Accessed Dec. 29, 2010.
- Dictionary of cancer terms: B. National Cancer Institute. http://www.cancer.gov/templates/db_alpha.aspx?expand=B. Accessed Dec. 29, 2010.
- Moynihan TJ (expert opinion). Mayo Clinic, Rochester, Minn. Dec. 29, 2010.


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