[Pseudomalignant, hyperacute circumscribed myositis. Contribution and limitations of echography. Review of the literature. Apropos of a case].

The very sudden onset of a painful muscular tumefaction was suggestive of a para-ostal osteosarcoma or myosarcoma. Ultrasound imaging showed a heterogeneous echogenic mass with several extending shadow cones, raising the possibility of the benign nature of the lesion, but urgent operation showed the pseudomalignant circumscribed myositis nature of the affection.