Q: How can I tell a tumor from a cyst?

A: A cyst is a sac containing air, fluid and semi-solid materials. A tumor is any abnormal mass of tissue that forms when cells grow and divide more than they should.

The vast majority of cysts are benign, meaning noncancerous. Cysts typically go away on their own and do not require treatment, although some people choose to have cysts surgically removed for cosmetic or pain management reasons. Recovery after surgery removing cysts above the skin lasts a few weeks.

In some cases cysts can contain cancerous materials or be large enough to damage organs, requiring surgical treatment. Recovery after surgery removing cysts under the skin, such as ovarian cysts, could last up to 12 weeks.

Cysts and tumors can appear anywhere on the body, and because determining the difference between the two can be difficult, people should seek medical attention if they notice an abnormal lump.

Doctors typically cannot tell a cyst from a tumor by physical appearance alone. For diagnosis, doctors will use imaging technology, such as sonograms, CT scans, ultrasounds and mammograms, to properly identify the lump and its severity.

There are three main types of tumors: benign, premalignant and malignant:

  • Benign tumors do not invade nearby tissue or spread to other parts of the body. Common benign tumors include polyps, moles and fibroids.

  • Premalignant tumors contain cells that are not cancerous but have the potential to become cancerous.

  • Malignant tumors contain cells that can or already have invaded and destroyed nearby tissue and can spread to other parts of the body. Common types of malignant tumors include carcinoma, lymphoma and leukemia.

For benign tumors, treatment is necessary only if the tumor becomes big enough to damage other organs. Surgery can effectively remove benign tumors.

Malignant tumors always require treatment. Depending on the stage of the tumor, chemotherapy, radiation, surgery or a combination of the three are recommended to stop or slow the growth of excess cells. Treatment also is recommended for premalignant tumors.

If you find a lump on your body, always seek medical attention.

Yu Yu Thar is a hematology/oncology specialist and attending physician at Mercy Fitzgerald Hospital in Darby.