A palpable mass in the musculoskeletal system is a common reason for consultation. The main issue is that a malignant tumor must not be missed. Inappropriate initial treatment can have direct consequences on the risk of local recurrence, the patient's future function and life expectancy. A mass more than 5cm in diameter, a subfascial location and a recent increase in size are signs that should lead the physician to question whether the lesion is truly benign and to carry out diagnostic examinations. MRI is the gold standard imaging exam. Biopsy, which is now mainly percutaneous and imaging-guided, must be performed for any subfascial mass more than 5cm long or a smaller mass with a high risk of postoperative functional sequelae. Referring the patient to a specialized cancer center has direct benefits on the patient's recurrence-free survival and reduces time lost during the diagnostic and treatment phases. For malignant tumors, surgical treatment requires resection margins that comply with cancer guidelines. Preservation of the limb and its function may require multidisciplinary reconstruction techniques. Pre- or post-operative radiation therapy or chemotherapy should be proposed only after discussion in a multidisciplinary team meeting.