A defined piece of single-stranded nucleic acid which is used to identify specific complementary-sequence nucleic acid molecules in an assay intended to be used to evaluate a clinical specimen to detect and/or monitor B-cell malignancies. Genetic changes associated with B-cell malignancies are typically associated with chromosomal translocations and gene rearrangements involving various genes/loci such as cyclin D1 (CCND1), immunoglobulin heavy or light chain genes (e.g., IGH, IGK, IGL), myc, and B-cell lymphoma genes (e.g., BCL1, BCL2).