Flow cytometric detection of B-clonal excess in fine needle aspirates for enhanced diagnostic accuracy in non-Hodgkin's lymphoma in adults.
Fine needle aspiration (FNA) cytology is a valuable aid to diagnosis and tumour staging in patients with non-Hodgkin's lymphoma. These tumours are often multicentric and involve sites such as the liver or the spleen which are not easily accessible to surgical biopsy. Particularly with splenic involvement, there is a diagnostic problem of morphologically distinguishing the lymphoma cells in an admixture of normal lymphocytes. Since most lymphomas in adults are of B-cell origin, we studied the diagnostic value of adding a surface immunoglobulin (sIg) light chain analysis to the cytological evaluation of FNAs. B-clonal excess was determined by flow cytometric analysis of the sIg light chain distribution and a monoclonal finding was considered diagnostic of lymphoma. In primary diagnostic procedures the light chain analysis established a diagnosis of lymphoma in 5/14 (36%) aspirates from patients with poorly differentiated tumours. Fine needle aspirates performed as part of staging procedures were morphologically normal or inconclusive in 19 cases; in seven of these (37%) lymphoma involvement was diagnosed by the light chain analysis. Diagnostic precision was enhanced by combining morphological and immunological evaluation of fine needles aspirates in patients with established or suspected non-Hodgkin's lymphoma.