Introduction to FNA and Salivary Gland Neoplasia

Salivary gland fine-needle aspiration (FNA) represents one of the most challenging areas of cytopathology. This is due in part to the wide range of lesions, both reactive and neoplastic, that can be encountered in the more than 500 salivary glands present in the human body. In fact, histologically (and cytologically), salivary gland tumors have been described as one of the most heterogeneous groups of human tumors; over 40 subtypes of neoplasms have been reported. An additional challenge for salivary gland FNA is the significant cytomorphologic diversity and overlap between many benign and malignant salivary gland tumors. In general, ancillary marker studies are of limited value in solving this problem because many salivary gland tumors have a similar composition of epithelial and myoepithelial cells. With all of these hurdles to overcome, it is quite impressive that salivary gland FNA emerges as an accurate and effective tool for diagnosing this complex group of lesions. Currently, FNA has gained wide acceptance as a first-line procedure in the evaluation of a salivary gland mass. In this book, we use an algorithmic approach (see Chapter 3) to guide you through the principles of salivary gland cytology, pointing out pitfalls, limitations, and differential diagnoses along the way, to allow you to use salivary gland FNA accurately and effectively.

FNA was first described in 1847 by Kun, and later, in the 1930’s, it was reintroduced and promoted by Martin and Ellis. While FNA remained popular in Europe and particularly in Scandinavian countries, it is only in the past 30 years that it has seen a resurgence in popularity in the United States. Currently, FNA is used extensively throughout the country for the assessment of both palpable and deep-seated lesions in most anatomic sites. FNA is performed manually by cytopathologists, clinicians, and surgeons for the assessment of palpable masses, and it is performed under ultrasound or CT-guidance for nonpalpable deep-seated or cystic lesions. It is considered standard of care to use FNA as an initial step in the evaluation of any thyroid nodule, and more and more it is being used to provide a preoperative diagnosis and thereby guide the clinical management of patients presenting with a salivary gland mass.