Kappa/Lambda Light Chain, ISH with Interpretation

Test Code

70042X

CPT Codes
88365, 88364

Preferred Specimen

Formalin-fixed paraffin embedded tissue in IHC specimen transport kit

Other Acceptable Specimens

Seven 4-micron unstained sections

Instructions

Do not place labels with adhesive backing on slides. Use pencil or xylene-resistant pen to write on the frosted end of the slide only.

Transport Temperature

Room temperature

Specimen Stability

Room temperature: Indefinite
Refrigerated: Indefinite
Frozen: Unacceptable

Methodology
In-Situ Hybridization (ISH)

FDA Status
This test was developed and its analytical performance characteristics have been determined by Quest Diagnostics. It has not been cleared or approved by the U.S. Food and Drug Administration. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.

Setup Schedule

A.M. Sets up 5 days a week.

Clinical Significance

This test is used to evaluate the genetic expression of kappa and lambda light chains in fixed lymphoid tissue or bone marrow. An atypical ratio of kappa-expressing to lambda-expressing cells can help support a diagnosis of plasma cell neoplasm or B-cell lymphoma [1,2].

Immunoglobulin comprises 4 polypeptide chains: 2 heavy chains and 2 light chains (kappa or lambda). Light chains can be found on the surface of B cells and in the cytoplasm of plasma cells. Restricted expression of kappa or lambda light chains can be an indication of B-cell lymphomas or plasma cell neoplasms, which include monoclonal gammopathy of undetermined significance, plasmacytoma, and multiple myeloma. Multiple myeloma and other plasma cell neoplasms may cause amyloidosis, which can lead to organ dysfunction [3].

This test is used to evaluate the expression of kappa and lambda light chains when fixed tissue or a limited amount of biopsy tissue is obtained. When sufficient fresh tissue is available, flow cytometry can be used to achieve high sensitivity over a broad dynamic range of protein expression. Serum kappa/lambda light chains can also be used to assist in the diagnosis of plasma cell disorders as well as in monitoring disease activity and treatment. Kappa/lambda light chain in situ hybridization cannot detect small amounts of surface immunoglobulin present on most resting B cells [1,3].

Interpretation of this test is performed by a qualified pathologist. The significance of the result should be determined in the context of pertinent clinical and family history, findings of physical examinations, and other diagnostic tests.

References
1. Guo L, et al. Mod Pathol. 2018;31(3):385-394.
2. Weiss LM, et al. Am J Pathol. 1990;137(4):979-988.
3. National Cancer Institute. Plasma cell neoplasms (including multiple myeloma) treatment (PDQ®)-health professional version. Accessed September 1, 2021. https://www.cancer.gov/types/myeloma/hp/myeloma-treatment-pdq

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.