Aim: To prove, if fine needle aspiration (FNA) is sufficient for detection of t(14;18) in lymph node infiltrated by follicular lymphoma (FL). To determine value of molecular remission in lymph node in patients in complete and molecular remission. Methods: First we tested t(14;18) in paired-specimens taken by FNA and by classical biopsy (from autopsies and operation biopsies). We continued to perform FNAs guided by ultrasound (US) in patients with easy accessible lymphadenopathy, t(14;18) was tested by FISH (fluorescent in situ hybridization) and by PCR (polymerase chain reaction). FNA of near the same lymph node was repeated in suitable patients in complete (CR) and molecular remission. Results: We tested for t(14;18) 22 paired samples (FNA vs. biopsy). 1/22 (4.5 %) FNA was negative compared to the biopsy. 31 FNA of lymph node guided by US were done, success of FNA was 100 % in advanced FL. FISH identified t(14;18) in 89 %, PCR in 67 %. 12 cases of FNA were done in CR (CT and PET) and molecular remission in blood (PCR): in 4/12 cases samples were not taken for technical reason, in 3/12 FNA fibrosis was detected. 6/7 patients with non-diagnostic FNA are in remission (median 19 months), 1 patient relapsed. 5/12 FNA were diagnostic (in 4 patients), t(14;18) was identified in 5/5 (100%) cases. 3 patients relapsed 3, 6 and 12 months later, 1 patient remains in remission (>20 months), in spite of repeated FNA identified t(14;18) after 12 months again. Conclusion: FNA is potentially suitable for detection t(14;18) in lymph nodes in FL. Persistence of t(14;18) in lymph node in CR is relatively frequent and this could be considered as real minimal residual disease. Further study is needed to define its biological importance, because persistence of t(14;18) in lymph node does not mean clinical relapse.

        Key words: t(14;18), follicular lymphoma, fine needle aspiration, minimal residual disease, FISH, PCR