Impact of laboratory work-up of lymphoma guidelines on cytopathology practices.

A multi-society expert panel recently published evidence-based guidelines and recommendations for the primary diagnosis and classification of lymphoma, which included a public comment period. The guideline concludes: "primary diagnosis and classification of lymphoma can be achieved with a variety of specimens." The guideline recommends that fine-needle aspiration biopsy (FNAB) cytomorphology not be used without ancillary testing, and that either flow cytometry or immunohistochemical immunophenotyping be performed for any type of specimen. Either excisional or core biopsy should be obtained when there is a high suspicion of lymphoma, and excision is recommended when feasible for Hodgkin lymphoma primary diagnosis. The use of cerebrospinal fluid to diagnose central nervous system lymphoma is discussed. For any patient with initial negative biopsy or fluid specimens and a high suspicion of lymphoma, additional tissue samples should be obtained. Additional molecular testing and good practice statements are summarized in the guideline. Cytopathologists should continue to advocate for judicious use of lymph node FNAB as an excellent triage tool that may require additional tissue biopsy for definitive diagnosis.