Automated molecular genetic DNA analysis for detecting B-cell non-Hodgkin's lymphoma in cytologic specimens

In fine needle aspiration cytology, conventional morphologic and immunocytologic criteria are often insufficient for distinguishing the mixed type of follicular lymphoma (NHL) from reactive lymphoid hyperplasia (RLH). For improving cytodiagnosis, we adapted computer-assisted polymerase chain reaction (PCR) assays on cytologic specimens. These novel techniques aim at fluorescence-based sequencing and sizing of PCR products that result from NHL-specific markers, such as the chromosomal t(14;18) (q32;q21) translocation and the CDR3 regions of expanded B-cell neoplasia.

Aspirates from eight cases with mixed-type follicular NHL and from nine cases with a cytologic finding of RLH were investigated by PCR and with an automated laser scanning system.

PCR detected the t(14;18) translocation in 5/8 B cell NHL samples and 1/9 RLH samples. By means of automated DNA sequencing, two of the five positive probes in the group of NHLs were identified as false positive. The CDR3 regions of expanded B-cell clones were found in four of eight NHL aspirates by means of PCR and computer-assisted analysis.

This study proved the reliability of automated genetic assays for diagnosing low grade B-cell NHLs in aspirates since false positive results are excluded.