An update of diagnostic strategies using molecular genetic and magnetic resonance imaging techniques for musculoskeletal tumors
ABSTRACT Rheumatologists may be incidentally confronted by bone and soft tissue lesions presenting in and around joints that require early recognition and appropriate referral. The diagnostic and therapeutic management of patients with musculoskeletal tumors is critically dependent on a multidisciplinary approach. Advances, particularly in the fields of histopathology, molecular (cyto)genetics and radiologic imaging techniques, have resulted in significant improvements in reaching a correct (differential) diagnosis, essential for implementing optimal treatment modalities. Magnetic resonance imaging is becoming increasingly important in planning preoperative and postoperative management strategies, and should precede all invasive procedures. Improvements in the fields of immunohistochemistry, together with the realization that certain tumor groups may be associated with specific genetic alterations, has significantly improved diagnostic accuracy. Additionally, the presence of certain genetic alterations within the tumoral genome have been found to be of prognostic value, and the hereditary context recognized for a number of specific bone and soft tissue tumors should be taken into account in the management of a patient with such a neoplasm. It is envisaged that an increasing understanding of the molecular biology and histogenesis of individual musculoskeletal tumor types will lead to tailor-made therapeutic options and consequently prognostic improvements. This update serves to highlight some important recent developments in fundamental and diagnostic aspects of musculoskeletal tumors. Abbreviations:CT computed tomography, MRI magnetic resonance imaging, RT-PCR reverse transcriptase polymerase chain reaction Bone and soft tissue tumors represent a heterogeneous and complex group of lesions arising as a consequence of neoplastic transformation within structures derived from the embryologic mesoderm and neuroectoderm, and are currently classified on a histogenetic basis according to the mature tissues they might resemble . Musculoskeletal neoplasms regularly present as a swelling in the vicinity of joints. Consequently, a rheumatologist may occasionally be confronted with a differential diagnosis which includes a benign or malignant soft tissue lesion and, as such, he or she need be aware of these tumors and be able to initiate the necessary and appropriate referral. Benign soft tissue lesions seen in the hospital setting outnumber their malignant counterparts by a margin of approximately 100:1. Malignant soft tissue tumors (sarcomas) are rare and represent about 1–2% of all cancers and cancer deaths in adults; in the US roughly 5,000 new cases are diagnosed annually, compared with 90,000 cases of lung cancer and 180,000 cases of breast cancer . In children, however, soft tissue sarcomas are relatively more common, accounting for approximately 10% of all malignant solid tumors. They may indicate a hereditary predisposition for cancer, for example, Li-Fraumeni syndrome, hereditary retinoblastoma, neurofibromatosis I, and the Beckwith-Wiedeman syndrome [3–8]. Interestingly, there appears to be an increasing incidence in sarcomas. Whereas this may primarily be a consequence of the improvement in available diagnostic modalities, the development of new diagnostic techniques and an increasing interest in this group of tumors [9••], the use of certain treatment strategies (radiotherapy regimens and alkylating chemotherapeutic agents) is known to predispose to sarcomatous transformation. Primary malignant bone tumors are considerably rarer than soft tissue sarcomas, accounting for less than 1% of all cancer deaths [1,9••]. Patients presenting for the first time with a musculoskeletal tumor frequently pose a diagnostic dilemma, and optimal management requires a multidisciplinary approach involving the primary physician, radiologist, pathologist, orthopedic surgeon, and oncologist. Because the distinction between reactive, benign, and malignant lesions may occasionally be extremely troublesome, careful and accurate clinical history taking and assessment, and appropriate radiologic imaging followed by a properly performed biopsy are essential in reaching a correct (differential) diagnosis, critical for deciding on the optimal treatment modalities for the individual patient. Advances and technical refinements, particularly in the fields of histopathology, molecular (cyto)genetics, and radiology have significantly improved our ability to reach an accurate clinical (differential) diagnosis, ensuring appropriate patient management. This review details a selection of these recent advances, and emphasizes the importance of a multidisciplinary approach to the patient with such tumors for optimal diagnostic and treatment results.