The persistence of t(14;18)-bearing cells in lymph nodes of patients with follicular lymphoma in complete remission: the evidence for 'a lymphoma stem cell'.

Monitoring of t(14;18) in blood or bone marrow in follicular lymphoma (FL) remains controversial. We attempted to monitor t(14;18) in lymph nodes by ultrasound-guided fine needle aspirations (UG-FNA). First, we confirmed t(14;18) in 27/31 UG-FNAs of lymph nodes with fluorescent in situ hybridisation (FISH) and/or polymerase chain reaction (PCR) in patients with advanced disease. In complete (CR) and molecular remission, there were repeated 18 UG-FNAs in 17 patients. Five of 18 UG-FNA were technically unsuccessful and 6/18 samples contained fibrosis. Despite that, these patients had a better prognosis. In 7/7 aspirations in six patients, t(14;18) was detected. Three patients are still in CR, even one of them remains in long lasting remission despite two consecutive evidences of t(14;18) in UG-FNA. Another three of these patients relapsed a few months after UG-FNA. This study is proof of the principle of the detection of residual t(14;18) bearing cells in previously involved lymph nodes despite patients being in remission.