The evaluation of a soft-tissue mass in the extremities.

A soft-tissue mass in an extremity may present a diagnostic dilemma for the evaluating surgeon. A decision either to observe or remove the mass is required. An algorithm can assist in the decision-making process. A careful history may aid in determining the etiology. A history of thigh-muscle trauma, for instance, may suggest myositis ossificans as the diagnosis of a malignant soft-tissue tumor. A large, firm mass that is fixed to deep structures or located within muscle should prompt the following studies: (1) plain radiographs of the extremity; (2) an ultrasound study of the mass; and (3) a three-phase technetium 99m methylene diphosphonate bone scan.