Detection of monoclonality in B-cell lymphomas using the polymerase chain reaction in paraffin-embedded tissues

BACKGROUND: Clonal rearrengements of immunoglobulin are useful in the diagnosis of B-cell lymphomas. The value of the polymerase chain reaction (PCR) with consesuated primers in the variable (V) and joining (J) region is now well established. METHODS: Forty cases of B-cell lymphomas and 10 patients with reactive lymphoid proliferations have been studied. All cases were studied with two different semiacotated techniques, with similar primers in the J region (LJH and VLJH) and changing the primers of the V region (Fr2A and Fr3A). RESULTS: A 100% specificity and positive predictive value were obtained with both techniques, The sensitivity was 90% with Fr2A and 82% with Fr3A, but in 20% of the studies with Fr2A the extracted DNA was insufficient to perform the study while it could be done with Fr3A in all cases. The negative predictive value was 76% with Fr2A and 58% with Fr3A. CONCLUSIONS: Both techniques showed a good sensitivity, optimal specificity and positive predictive value, with low negative predictive value. Although the results are somewhat higher with Fr2A, this technique needs well preserved DNA and it can be an important set back when we deal with formaldehyde fixed, paraffin embedded tissues.