An inflammatory disease of the muscles closest to the center of the body. It causes weakness, inability to stand, climb stairs, lift, or reach. It may also cause muscle pain and difficulty swallowing, and may affect the lungs and heart. Having polymyositis increases the risk of certain types of cancer.
Last updated: 2016-01-06
Source: The National Cancer Institute's Dictionary of Cancer Terms (http://www.cancer.gov/dictionary)