Value and limitations of fine-needle aspiration cytology in diagnosis and classification of lymphomas: A review

The fine needle aspiration (FNA) cytologic diagnosis of non-Hodgkin's Hodgkins lymphoma (NHL) depends upon finding a relatively monotonous population of lymphoid cells in smears. Lymphomas have successfully been classified by FNA cytology following the prevalent histologic classifications. The success rate of FNA cytology ranges from 80%-90% in diagnosis of NHL and from 67.5%-86% in its subtyping. The cytodiagnosis of Hodgkin's disease (HD) depends upon demonstration of Reed-Sternberg cells or Hodgkin's cells amongst appropriate reactive cell components, The diagnostic accuracy of FNA cytology for HD has also been invariably high (>85%). Yet, the role of cytology in primary diagnosis, subclassification and management of patients with lymphoma remains controversial. The differential diagnostic pl-ob leins for NHL include a group of small round cell tumors, nonlymphoid acute leukemias and HD. Reservations have been expressed regarding the efficacy of cytology in separating florid reactive hyperplasia from low-grade malignant lymphoma. The reported cytodiagnostic accuracy for follicullar lymphomas and nodular sclerosis type of HD is less compared to other subtype of NHL and HD respectively since nodular pattern and sclerosis are strict histologic criteria which can not be appreciated in cytologic preparations. Entities like apical lymphoproliferative disorders, peripheral T-cell lymphomas and Ki-1 positive anaplastic large cell lymphomas pose diagnostic challenges to cytologists. Despite these limitations, FNA cytology remains the first line of investigations (screening test) used ill cases of lymphadenopathy: Besides initial diagnosis of lymphoma, it helps in detection of residual disease, recurrences and progression of low-grade to high-grade lymphoma, and helps in staging the disease. Availability of prior FNA cytology report facilitates the histologic diagnosis and classification of NHL. Various special ancillary techniques are now being performed on lymph node aspirates to diagnose lymphoma versus other malignancies, and to decide the functional character of lymphomas and their clonal nature. (C) 1999 Wiley-Liss, Inc.