A Basic Approach to Lymph Node and Flow Cytometry Fine-Needle Cytology

According to the World Health Organization (WHO), the new classification of lymphomas is mainly based on morphological, immunophenotypical, and molecular criteria. Consequently, this new approach has led from the substantial role that architecture played in the past to a secondary panel highlighting the role of fine-needle biopsy (FNB). Applied together with other ancillary techniques, such as flow cytometry (FC), FNB is a potential tool for the diagnosis of lymphomas, and enlarged lymph nodes represent an excellent target for the implementation of this technique. Despite the difficulties inherent in this technology, which might pose problems in differential diagnosis, in the majority of cases this joint work allows an accurate diagnosis of malignancy and even correct subcharacterization in routine lymphomas. Additionally, in selected cases, other molecular techniques like FISH and PCR can also be performed on FNB specimens, helping in the characterization and diagnosis of lymphomas. In this review, we discuss the basic aspects of the combination of FNB cytology and FC in the diagnosis and subclassification of lymphomas. The preanalytical phase is extensively discussed. The advantages, disadvantages, and technical limitations of this joint work are addressed in general and in terms of the accurate subclassification of lymphomas.