Cysts on the thyroid are fluid-filled sacs that develop on the thyroid gland. Fluid-filled cysts are benign; but when solids and fluids form the cyst, there is an increased chance of malignancy, according to Cedars-Sinai. Complex cysts on the thyroid contain both fluids and solids, which a doctor can biopsy to determine if there is a malignancy. Doctors draw fluid from the cyst and test it to determine if cancer is present.
Cysts on the thyroid rarely cause symptoms; but when they become enlarged, the cyst may cause pain in the neck. Some patients may also detect the growth under their skin and notice that the area is tender. The neck size may increase as well when a thyroid cyst is large. When a cyst becomes enlarged enough to notice, it may be the only symptom that patients experience.
Cysts that are growing on the thyroid quickly may cause difficulty with swallowing. This can become a serious condition, and a doctor should evaluate the condition immediately to test for thyroid cancer, according to the Mayo Clinic. Thyroid nodules are more likely to be cancerous if they grow rapidly or cause difficulty when swallowing. Large cysts that make it difficult to breathe or swallow may be removed with surgery even if they are not malignant, according to the Mayo Clinic.
Change in Voice
When thyroid cysts press on the vocal cords, the voice may become hoarse, according to MyThyroid.com. This symptom is rare and usually occurs with rapidly growing cysts or nodules on the thyroid.
Excess Hormone Production
When thyroid nodules produce an excess amount of the thyroid hormone, thyroxine, symptoms of weight loss, nervousness and a rapid heartbeat may occur. Hormones may be given to patients to stop the gland from producing excess amounts on its own, according to the Mayo Clinic.