Sarcoma and look-alikes: the important role of ultrastructural evaluation.

Due to the variable light microscopic appearance of sarcomas, a large number of neoplasms may need to be considered in the differential diagnosis in some situations. In difficult cases, the surgical pathologist must approach the differential diagnosis using ancillary diagnostic techniques and should do so in an orderly fashion, recognizing that arriving at the correct diagnosis is without a doubt the most important goal. It is also imperative to take into account the expense and time that may be involved in arriving to the definitive diagnosis, which could influence how the workup is conducted. Therefore, the most reasonable route to address the differential diagnosis in order to make a final solid diagnostic assessment should be taken. Whether immunohistochemistry, electron microscopy, cytogenetics, and/or molecular diagnostics should be employed in a given case becomes the dilemma. In some instances a combination of the above-mentioned techniques is important not only to obtain an unequivocal diagnosis, but also to provide important additional information regarding prognosis and to facilitate the patient's management.