Differential diagnosis of musculoskeletal tumors with magnetic resonance imaging

Musculoskeletal neoplasms are rare, and both the medical history and compla ints of the patients are usually uncharacteristic and of limited informatio n. After a clinical evaluation and biplane conventional radiography, the cl inician must classify the patient as having a nonprogressive or progressive primary benign, primary malignant, or metastatic bone tumor. In the case of a probably benign, nonprogressive bone tumor, the patient ha s to be observed continuously or an additional biopsy should be performed. In the case of a probably malignant lesion,the patient should be referred f or further staging and treatment to an orthopedic oncologist. Conventional biplane radiography, scintiscan, computed tomography scan,and magnetic reso nance imaging (MRI) are indispensable in staging and treatment planning for patients with musculoskeletal tumors. For limb salvage procedures, delinea tion of the tumor from adjacent tissue structures is crucial. Hence, MRI of the entire anatomic structure involved, together with adjacent joints, is of the utmost importance, both in the coronal and axial planes. The significance of MRI in clinical followup depends on keeping the sequenc es and imaging planes used constant. Differentiating pseudotumors from true neoplasms still poses a challenge. The cellular pattern and matrix charact eristics of a lesion cannot definitely be identified as neoplastic even wit h application of all imaging modalities including MRI. Information on epide miology, clinical picture, radiology, and histology of the lesion is necess ary to draw a firm conclusion. Biopsy is still the first choice in making t he diagnosis.