Diagnostic challenges in aspiration cytology of the salivary glands

The main goal of fine-needle aspiration (FNA) of salivary gland lesions is to assist the clinician in the management of patients who present with a mass lesion. Cytologic examination aims to determine, if a process is inflammatory and/or reactive, benign or malignant neoplasm and if possible renders a specific diagnosis. It has been argued that in the area of salivary gland tumors, surgical management relies less heavily on a specific preoperative diagnosis, because almost all neoplastic salivary gland lesions will undergo surgical excision. However, knowing beforehand if a lesion is malignant or benign, will aid in planning surgery and may prompt or postpone decisions for surgical intervention. The salivary glands are unique in their histologic complexity and morphological variability of tumors, which is reflected in the cytologic material. In addition to the overlapping morphologic patterns of salivary gland tumors, they also represent relatively rare lesions, thus making it more difficult to acquire diagnostic expertise in FNA. Other than approaching salivary gland tumors by a description of single entities in their benign and malignant categories, we favor a more practical approach to diagnosis based on the key morphologic features noted in FNAs. This article addresses differential diagnoses according to the predominant cytologic presentation with attention to the cell type and size, nature of the cytoplasm, and the smear background.