Fine needle aspiration biopsy and flow cytometry in the diagnosis of lymphoma

Fine needle aspiration biopsy (FNAB) is emerging as a technique of potential value in the diagnosis of benign and malignant lesions in areas such as the breast and thyroid gland. Its place in distinguishing reactive from neoplastic lymphoid proliferations, when compared to the established practice of excision biopsy and histopathology, continues to undergo evaluation. Morphology alone discriminates poorly between atypical or lymphoproliferative disorders as seen in the presence of Epstein-Barr or human immunodeficiency virus. Furthermore the polymorphic populations of follicular lymphoma may mimic reactive changes. In addition previous classifications of these tumours using working formulation or Kiel classification relied heavily on architecture, which is a feature not reflected in cytology smears. The World Health Organisation approach includes clinical features, immunophenotyping and cytogenetic profiles to define neoplasms of immunohaematopoietic tissues. Flow cytometry on fine needle aspiration biopsy offers additional advantages in being rapid and objective in quantitatively as well as qualitatively documenting cell surface characteristics. All patients referred for this procedure to Tygerberg Academic Hospital with suspected nodal or extranodal lymphoma between January 2002 and December 2004 were analysed. In each case flow cytometry and cytomorphology were correlated with histopathology on tissue biopsy, bone marrow examination and clinical follow-up for confirmation of diagnosis. Results of the 124 cases were tabulated and statistically processed. Eighty-one met the inclusion criteria, thirteen (16.1%) were not malignant, two (2.5%) were falsely negative, two (2.5%) were equivocal needing histology and in the remaining sixty-four (79%) diagnosis was achieved.

Fine needle aspiration coupled with flow cytometry can reliably distinguish between nodal and extranodal neoplastic B-cell population. It is concluded that appropriate use, in a collaborative multidisciplinary setting, may eliminate the need for surgical procedures in many cases.

These advances are not widely recognised and this is particularly true in South Africa. Accordingly, such an approach has been prospectively evaluated in the Western Cape showing that the combination of ready availability and diagnostic accuracy, after an initial learning curve, allow accurate characterisation of haematologic malignancies so that excision biopsy may be reserved for specific further studies to provide data not available from this less invasive procedure.