Fine needle aspiration in the diagnosis of bone tumors.

Fine needle aspiration (FNA) is an important part of the preoperative diagnosis in bone tumors. The diagnosis must be based on clinical, radiologic and morphologic correlation. In palpable lesions, FNA is performed on the most accessible part of the tumor. Deep-seated and/or non-palpable lesions need radiologic guidance. Material from the FNA can be used for additional examinations, i.e. electron microscopy, immunocytochemistry, cytochemistry, DNA-ploidy analysis, chromosomal analysis and molecular genetics. Those examinations are of particular importance in the primary and differential diagnosis of Ewing sarcoma, osteosarcoma and chondrosarcoma. The majority of tumors in FNA aspirates can be classified as primary (benign or malignant) and metastatic tumors. Cellularity, pleomorphism, chromatin pattern, nucleolar structure, mitotic figures and necrosis are parameters of malignancy.