Fluorescence in situ hybridisation analysis of bone marrow trephine biopsy specimens; an additional tool in the diagnostic armoury.

Fluorescence in situ hybridisation (FISH) analysis is now widely employed in the diagnosis and risk stratification of a wide range of malignant diseases. While this technique is used successfully with formalin-fixed paraffin-embedded (FFPE) sections from numerous tissue types, FISH analysis of FFPE tissue sections from trephine biopsy specimens has been less widely reported, possibly due to technical limitations relating to the decalcification protocols employed. During the last 4 years FISH analysis has been carried out successfully in 42 out of 55 (76%) consecutive trephine biopsy specimens received as part of the standard diagnostic service at our institution. Samples decalcified using EDTA-based protocols were analysed successfully in 31/31 cases (100%), whereas only 11/24 samples (46%) decalcified using formic acid-based protocols were successful. In our experience, FISH analysis of trephine biopsy specimens is a highly reproducible technique and a very useful adjunctive tool in the diagnostic armoury; however, its use in a standard diagnostic setting relies on the use of EDTA-based decalcification protocols.

Fluorescence in situ hybridisation analysis of formalin-fixed paraffin-embedded tissue sections in the diagnostic work-up of non-Burkitt high grade B-cell non-Hodgkin's lymphoma: a single centre's experience.

AIMS: In recent years the genetic aberrations associated with diffuse large B-cell lymphoma and the new subtype described in the 2008 revision of the WHO classification, 'B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma and Burkitt lymphoma' have been increasingly well defined. Recurrent genetic abnormalities include rearrangements involving MYC (8q24), BCL2 (18q21) and BCL6 (3q27); as the prognostic and therapeutic implications associated with these abnormalities are clarified their accurate identification at diagnosis is becoming increasingly critical. We describe our experience of using a panel of fluorescence in situ hybridisation (FISH) probes on formalin-fixed paraffin-embedded tissue sections in the diagnostic work-up of 162 patients with non-Burkitt high grade B-cell non-Hodgkin's lymphomas (HG-BNHL). METHODS: BCL6, IGH-BCL2 and MYC status were determined prospectively in sequential patients presenting with HG-BNHL, with respect to the presence of rearrangements and copy number changes. Small numbers of samples were analysed retrospectively or were studied at relapse in previously untested patients. RESULTS: FISH analysis was successful in 160/162 (99%) cases, with abnormalities detected in 118/160 (74%). CONCLUSIONS: FISH analysis of formalin-fixed paraffin-embedded tissue sections is a highly reproducible technique with an excellent success rate for the detection of genetic abnormalities which will play an increasingly important role in improving risk stratification of patients with HG-BNHL.

Detection of cryptic and variant IGH-MYC rearrangements in high-grade non-Hodgkin's lymphoma by fluorescence in situ hybridization: implications for cytogenetic testing.

In recent years it has become increasingly evident that MYC rearrangements are not confined to classical Burkitt lymphoma (BL), but also occur in diffuse large B-cell lymphoma (DLBCL) and in the new subtype, "B-cell lymphoma, unclassifiable, with features intermediate between DLBCL and BL" (BCLU), which was recently described in the 2008 revision of the World Health Organization classification. The accurate identification of MYC rearrangements in these three subtypes of high-grade lymphoma is becoming increasingly critical both in terms of diagnosis of classical BL and in light of the prognostic implications in cases of DLBCL and BCLU. We describe three cases of high-grade lymphoma in which cryptic insertion events, resulting in clinically significant IGH-MYC rearrangements, were detectable using an IGH/MYC three-color, dual-fusion fluorescence in situ hybridization (FISH) probe set, but were not detected using break-apart MYC FISH probes, thus highlighting the limitations of using break-apart probes as a stand-alone test, particularly with the increased use of interphase FISH analysis of formalin-fixed, paraffin-embedded tissue sections in the diagnostic work-up of these patients.