Abstract
Fine needle aspiration cytology/biopsy (FNAB) is quite often one of the first tests for the initial evaluation of lesions/swellings which are accessible to the needle tracts. The technique has its limitations in certain cases owing to the non-representative or inadequate material aspirated or due to the confusion arising from the lack of histologic pattern as observed on a biopsy. An immediate rapid on-site evaluation (ROSE) is valuable in minimizing the limitations arising from the non-representative/inadequate material. The introduction and application of several ancillary modalities, like immunocytochemistry, molecular tests and the advancements in interventional radiology, has further revolutionized the diagnostic scope of FNA biopsy. Molecular tests on the FNAC samples can aid in the distinction of benign from malignant lesions, in determining the genetic abnormalities and genetic makeup of tumors that can be useful not only for making a more specific diagnosis but also for determining prognosis, response to therapy and for the selection of patients for targeted therapy. FNAB biopsies have an added advantage in comparison with the core needle biopsies for molecular analysis since they have a much lower contamination of stroma. The chapter will be discussing the advancements and the uses of these ancillary techniques in the field of FNAC.