Lymphoma Associated Chromosomal Abnormalities Can Be Easily Detected by FISH on Tissue Imprints. an Underused Diagnostic Alternative.

Detection of specific chromosomal abnormalities is essential in the diagnosis of several lympholiferative disorders. However, conventional cytogenetic studies are not frequently carried out from biopsies as it is in bone marrow (BM) specimens. On the contrary, FISH is usually performed on paraffin embedded tissue, an alternative with potential technical nuances both in its application and its interpretation. In our experience, FISH on tissue imprints is the ideal alternative to overcome these problems. In the present study, 46 tissue imprints and 17 BM smears from 43 patients with lymphomas were selected to investigate the presence of t(14;18)(q32;q21), t(11;14)(q13;q32), t(8;14)(q24;q32) and t(3;var)(q27;var). Representativity of the samples was assured prior to FISH by rapid May-Grümwald staining (Diff-Quick, QCA, Spain). Twenty imprints from reactive palatine tonsils and adenoids were used as negative controls. FISH was performed with specific dual-color dual-fusion FISH (D-FISH) probes for the first 3 translocations and a dual-color break-apart FISH probe for t(3;var)(q27;var) following the instructions of the probes supplier (Vysis, Inc). All except one sample (a BM smear stored at room temperature over 9 years), rendered satisfactory FISH hybridizations. In any case, all 43 patients could be successfully studied by FISH (the case referred above in which FISH failed in a first attempt was successfully analyzed using a different sample). The results supported the suspected diagnosis of follicular lymphoma in 22 patients, mantle cell lymphoma in 12 patients, large B-cell lymphoma in 5 patients, marginal zone lymphoma in 2 patients and B chronic lymphocytic leukemia in 2 patients. In one case, the observation of t(11;14) by FISH allowed to reclassify the case from follicular to mantle cell lymphoma and also to demonstrate clonal evolution by studying sequential tissue imprints stored for more than 6 years. Negative results also aided in the assignment of patients to proper diagnostic categories. FISH performed on tissue imprints and BM smears constitutes an optimal strategy for retrospective and prospective investigation of chromosomal abnormalities in lymphomas. Tissue imprints and BM smears conventionally stored at room temperature even for long periods of time can be safely used and sent by ordinary mail without special considerations for this purpose. Based on our experience we recommend to perform and routinely store tissue imprints whenever fresh tissue is available.