Almost 9,000 soft tissue sarcomas (and 2,500 bone sarcomas) are diagnosed annually in the United States; <1% of the 1,444,920 new cancer cases diagnosed in the United States in 2007. Benign soft tissue tumors outnumber sarcomas by approximately 100:1, increasing the yearly incidence of all soft tissue tumors to about 300 per 100,000.

The use of fine-needle aspiration (FNA) as a primary diagnostic tool in soft tissue lesions is still uncommon, resulting in the lack of experience among many cytopathologists. Lack of experience coupled with the ever-present sampling error in larger masses has led to the avoidance of FNA as the primary diagnostic tool in most medical centers.

The knowledge of general soft tissue surgical pathology cannot be overemphasized. All aspirates should be evaluated with the clinical and imaging data in mind. Cytopathologists, clinicians, and radiologists must work closely together to arrive at the best and most accurate diagnosis. Ancillary techniques, especially cytogenetics, should be employed whenever appropriate.

To give perspective on fine needle aspiration practice, we list here the most common soft tissue masses aspirated at the Institute of Oncology (IO), in Ljubljana, Slovenia. The FNA clinic at IO opened in 1959 and has a volume of approximately 10,000 annual aspirates in the last 20 years. In 2004, of these, 1,818 were aspirates of soft tissues (Table 36.1). To avoid confusion, we will list only the entities that are most common and well defined.