IGH FISH-CISH DNA probe split signal: An additional tool in clonality assessment of lymphoproliferative processes

BACKGROUND: The human IGH (immunoglobulin heavy) locus at chromosome 14q32 is frequently involved in different translocations of non-Hodgkin lymphoma (NHL). The split signal IGH FISH-CISH DNA probe (IFCD) is a mixture of two fluorochrome-labeled DNAs that binds the telomeric and the centromeric segments, on the IGH breakpoint respectively. Therefore IGH FISH DNA probe, split signal should detect any translocation involving the IGH locus at chromosome 14q32. The cytological diagnosis of pleural or peritoneal involvement by NHL may be hampered by scanty cellularity, concomitant reactive infiltrate and good differentiation of the cells. The aim of this study was to evaluate if the IGH FISH DNA probe, split signal may be helpful in the cytological diagnosis of pleural and peritoneal involvement by NHL. METHODS: We retrospectively tested the IGH FISH DNA probe, split signal on 15 cytological samples of NHL pleural and peritoneal effusions and 10 negative samples to assess the sensitivity and specificity of the probe. RESULTS: The IGH FISH DNA probe detected split signals in a significant number of cells in 12 out 15 positive cases and in none of the 10 negative controls. CONCLUSIONS: The IGH FISH DNA Probe, is highly sensitive for the detection of translocations involving the IGH locus on effusion’s cytological samples, whereas it is not specific for the single pathological sub-types. The procedure is highly effective in mixed polymorphous cell populations and in scantily cellulated samples in which other procedures may be hampered