Small Lymphocytic Lymphoma, FISH, Tissue
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Small lymphocytic lymphoma (SLL) is the non-leukemic form of chronic lymphocytic leukemia (CLL), the most common adult leukemia in North America. The most common cytogenetic abnormalities detected in CLL are deletions of 6q, 11q, 13q and 17p, trisomy 12 and the occasional occurrence of IGH translocations at 14q32. Cytogenetics has proven to be a reliable predictor of outcome for patients with CLL. It is unknown if SLL has the same prognostic significance when these genetic abnormalities are observed.
This fluorescence in situ hybridization test detects an abnormal clone in approximately 65% of patients with SLL. Patients with t(11;14)(q13;q32) associated with CCND1/IGH fusion, have mantle cell lymphoma which can be distinguished from SLL and other B-cell lymphomas with this assay. Patients with t(14;18)(q32;q21) or t(14;19)(q32;q13.3) may have an atypical form of SLL or another low-grade B-cell lymphoma.
Detecting a neoplastic clone associated with the common chromosome abnormalities seen in patients with small lymphocytic lymphoma (SLL) and other low-grade B-cell lymphomas.
Distinguishing patients with 11;14 translocations who have mantle cell lymphoma from patients who have SLL.
An interpretive report is provided.
A positive result is detected when the percent of cells with an abnormality exceeds the normal cutoff for the probe set.
A positive result is not diagnostic for small lymphocytic lymphoma, but may provide relevant prognostic information.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
This test is not approved by the FDA, and it is best used as an adjunct to existing clinical and pathologic information.
Fixatives other than formalin (eg, Prefer, Bouin) may not be successful for fluorescence in situ hybridization (FISH) assays. Although FISH testing will not be rejected due to nonformalin fixation, results may be compromised.
Paraffin-embedded tissues that have been decalcified are generally unsuccessful for FISH analysis. The pathologist reviewing the hematoxylin and eosin-stained slide may find it necessary to cancel testing.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
An interpretive report will be provided.
Clinical References Provides recommendations for further in-depth reading of a clinical nature
1. World Health Organization Classification of Tumours. Pathology and Genetics of Tumours of Haematopoietic and Lymphoid Tissues. Fourth edition. Edited by SH Swerdlow, E Campo, NL Harris. IARC Press, Lyon, France, 2008
2. Dohner H, Stilgenbauer S, Benner A, et al: Genomic Aberrations and Survival in Chronic Lymphocytic Leukemmia. N Engl J Med 2000;343(26):1910-1916
3. Nowakowski G, Dewald G, Hoyer J, et al: Interphase Fluorescence in situ Hybridization with an IGH Probe is Important in the Evaluation of Patients with a Clinical Diagnosis of Chronic Lymphocytic Leukemia. Brit J Haematol 2005;130(1):36-42