Methodology: CISH

Clinical Significance:
Kappa and lambda immunoglobulin light chains are expressed by plasma cells and plasmacytoid lymphocytes. They are also expressed, but less reliably detected, on B cells with weak cytoplasmic staining. However, immunoglobulin are also a major component of serum, leading to (in many tissue types) high background/non-specific staining which may obscure the detection/observation of light chain restriction among B lineage cells. This non-specific staining also impedes the assessment of light chain skewing in non-neoplastic populations. As all proteins are translated from mRNA, detection of mRNA transcripts can be a useful surrogate for protein expression and therefore in-situ hybridization for kappa and lambda mRNA transcripts can be used to determine the light chain restriction status for plasma cell and plasmacytoid B cell populations. Subcellular Localization: Cytoplasmic

Organ: Blood/Bone Marrow

Disease State: Amyloid Type Analysis

CPT Code(s): 88365 or 88364 (reference only; CPTs may vary)

Turnaround Time: Within 1-2 business days of receipt

Schedule: Monday - Friday

Specimen Requirements:
• Formalin-fixed, paraffin-embedded (FFPE) tissue block or cell block - OR - • 1 unstained slide for each test requested plus 3-4 additional unstained slides cut at 4µm