Learning salivary gland cytology from the basics

Abstract

Head and neck cytology is primarily performed on fine-needle aspiration cytology (FNAC) specimens, most frequently obtained from lesions of the salivary glands, lymph nodes, thyroid, and tumors originating from the nasal cavity. The practice of head and neck cytology demands extensive knowledge and experience from the observer, as it deals not only with primary tumors but also metastatic tumors, and inflammatory and infectious diseases. Tumor lesions in the salivary glands are categorized into various histological types, including pleomorphic adenoma, Warthin tumor, and malignant entities, such as mucoepidermoid carcinoma and adenoid cystic carcinoma. It is crucial to comprehend the characteristics of frequently occurring tumors while being mindful of the limitations of making a diagnosis of salivary gland lesions through FNAC. Cytological diagnosis involves morphological observations, primarily using Papanicolaou (Pap.) staining, and metachromatic findings are examined using May-Grünwald-Giemsa (MGG) staining. The advantage of MGG staining lies in its usefulness for diagnosing hematological disorders, such as lymphomas and non-neoplastic lesions. Consequently, dry specimens are prepared for MGG staining. Some malignant tumors may lack significant atypia, and conventional malignancy criteria might not suffice for a definitive diagnosis. Therefore, the diagnostic approach for salivary gland tumors involves observing individual cell atypia and inferring the direction of cellular differentiation using Pap. staining. In addition, the observation of mucin and extracellular stroma using MGG staining is crucial.