LAUSR

Dear Editor We read with interest the article by Wang et al., “Diagnostic accuracy of fine-needle aspiration cytology for lymphoma: A systematic review and meta-analysis”, recently published in Diagnostic Cytopathology. The authors conclude that FNAC (fine needle aspiration cytology) is highly effective in the diagnosis of lymphoma but further studies assessing its accuracy in diagnosing specific types of lymphoma are required. We agree with the authors and we would like to add some comments. Difficulty in identifying specific lymphoma subtypes, variants and rare entities is certainly a limit of lymph node (LN) FNAC which has been emphasized by its detractors. Unfortunately, this limit has been used to discredit the procedure as a whole. This is unfair because LN-FNAC is used, in many cases, to exclude lymphoma and to diagnose metastases and lymphoma relapses indicating the primary tumor or the lymphoma type when possible. In this perspective, the recently proposed Sydney System for the performance, classification, and reporting of LN-FNAC has split the procedure in two diagnostic levels: the first level considers five diagnostic categories: inadequate, negative, atypical, suspicious, and malignant; the second level consists in identifying the specific benign or malignant entity. The first level is sufficient for most clinical requests, indicating whether the most appropriate management is follow-up only, repetition of FNAC or definitive histological diagnosis by core-needle or surgical biopsy. The second diagnostic level mainly depends on the availability of ancillary techniques. It obviously adds value to FNAC diagnoses, including specific lymphoma subtypes, but its lack does not diminish the clinical value of the first level. This point is even more relevant in extra-nodal lymphoproliferative processes, in which the simple diagnosis of lymphoma is more relevant—from a clinical point of view—than in LNs; furthermore, the variety of extranodal lymphoproliferative processes is generally more limited than in LNs. There are numerous studies assessing the value of FNAC in the diagnosis of extra-nodal lymphoproliferative processes; a formal analysis of the performance of FNAC for nodal and extra-nodal lymphoproliferative processes would be useful.