The intramuscular myxoma is a rare benign soft tissue tumor characterized by bland spindle-shaped and stellate cells embedded in hypovascular myxoid stroma. We report the isolated case of a 44-year-old female patient with an intramuscular myxoma in the anterior tibial muscle and report the clinical and radiographic findings. We performed an analysis of the GNAS gene mutation status with a positive finding. In difficult cases, recurrent tumors or small biopsies detection of a GNAS mutation can be useful to confirm the diagnosis of an intramuscular myxoma.
