Intramuscular myxoma is a rare benign tumor that contains myxoid tissue. It occurs in older people between 40 and 70 years of age. Usually, it is solitary and has a slow growth rate. Multiple myxomas have been seen in patients with fibrous dysplasias. The tumor is usually localized in a large muscle of the thigh, shoulder, or hip.
The CT appearance is a well-defined, homogeneous mass with a density lower than that of muscle. The mass typically does not enhance after administration of contrast material. It has low signal intensity on TI-weighted MR images and high signal intensity on T2-weighted images.