Detection of t(14;18) in follicular lymphoma by dual-color fluorescence in situ hybridization on paraffin-embedded tissue sections.

We studied the incidence of t(14;18)(q32;q21) in 54 patients with follicular lymphoma (FL) by dual-color fluorescence in situ hybridization on paraffin-embedded tissue sections (tissue-FISH) using probes for BCL2 and immunoglobulin heavy chain (IGH) genes. The t(14;18) was detected in 28 (56%) of 50 patients, who were successfully analyzed. On the other hand, BCL2 protein expression was detected in 45 (83%) of 54 patients evaluated by immunohistochemical staining. There was a discrepancy between t(14;18) and BCL2 expression. The absence of t(14;18) was associated with disease-free survival (P=0.02). There was no statistical difference, however, in overall survival and failure-free survival between the t(14;18)-positive and -negative groups. Tissue-FISH should be of great value to detect t(14;18) in FL because this method enabled us to demonstrate specifically t(14;18)-positive individual cells in neoplastic follicles on paraffin-embedded tissue sections. Furthermore, tissue-FISH can be applied to small specimens obtained from endoscopic biopsy or specimens obtained more than 10 years ago. We validated the usefulness of tissue-FISH as a diagnostic procedure and retrospective meta-analysis for malignant lymphoma.