The Lymph Nodes

Fine-needle aspiration (FNA) is the most useful minimally invasive approach in the evaluation of lymphadenopathy. The diagnostic accuracy of the procedure is increased with the use of ultrasound (US) to guide the needle to the significant intra-nodal area and avoid cystic areas, select the most abnormal lymph node, evaluate non-palpable lymph nodes, and obtain samples for ancillary tests. This chapter covers briefly lymph node anatomy and histology and clinical considerations as preamble to discuss in detail the various head and neck levels, paramount to facilitate the localization of a particular lymph node. The FNA diagnosis of lymph nodes is covered using a cell pattern approach, and select reactive, infectious/inflammatory, and neoplastic (lymphomas and metastasis) entities are discussed. Immunophenotype is also included in each lymphoma entity. US features of benign and malignant lymphadenopathies are also covered in detail and complemented with numerous illustrative images. The text is supplemented with relevant video clips, figures, and references.