Chromosome Analysis – Lymph Node

Test Overview

CPT Code(s)

88237, 88264, 88280, 88291

Methodology

Culture / Microscopy / Karyotype

Specimen Requirements

Container: Sodium Heparin (green top tube)

Optimal Quantity: 1 x 1 x 1 cm piece of non-necrotic tissue

Storage: Room Temperature

Stability at Room Temperature: 8 hours, then refrigerate

Transportation: Avoid freezing or heating over 35OC

Turnaround Time

Final report in 5 days for 90% cases

Test Details

Clinical Significance

A chromosome analysis on lymph node may be clinically significant to identify and diagnose acquired neoplastic conditions associated with lymphoma and indications such as, mantle cell lymphoma, T-cell lymphoma, B-cell lymphoma, follicular lymphoma, Burkitt lymphoma, MALT lymphoma, diffuse large B-cell lymphoma and anaplastic large cell lymphoma.  It may also be relevant in cases to confirm or exclude the diagnosis of lymphoma based on morphology and track progress of treatment.

Clinical Background

B-cell and T/NK-cell neoplasms are clonal tumors of mature and immature B-cells, T-cells or natural killer (NK) cells at various stages of differentiation.  B-cell and T-cell neoplasms in many respects tend to mimic stages of normal B-cell or T-cell differentiation. Several mature B-cell neoplasms have characteristic genetic abnormalities that important in determining their biologic features and can be useful in differential diagnosis.  These include the t(11;14) in mantle cell lymphoma, t(14;18) in follicular lymphoma, t(8;14) and variants in Burkitt lymphoma, and t(11;18) in MALT lymphoma.  Only a few T-cell neoplasms have thus far been associated with specific genetic abnormalities.  Anaplastic large cell lymphoma, ALK+, is defined by translocations involving the ALK (anaplastic lymphoma kinase) gene on chromosome 5, (t(2;5) and variants).  However, the molecular pathogenesis of most other T-cell and NK-cell neoplasms remains to be defined.  Chromosome analysis on lymph node serves as a diagnostic study for relevant acquired chromosomal aberrations in one test, whereas molecular studies are significant in cases where a diagnosis has been made or a suspicion exists and specific testing is targeted.

Methods

Lymph node samples are unstimulated.  They are harvested at 24 hours and if volume is sufficient, a 48 hour culture is also initiated followed by G-banding. Analysis is carried out by two certified technologists using manual metaphase scanning and karyotyping utilizing the Cytovision software.  Both technologists analyze the first 10 consecutive metaphases after which they are reviewed by the manager and reported by the director.

Interpretation of Results

The morphologic interpretation and correlation of results on all cases is performed by a board-certified doctoral level scientist (laboratory director). The final report identifies the chromosomal sex and modal chromosome number.  If abnormalities are present, they are explained in a paragraph which helps to clarify and correlate clinical findings with pathological morphology. FISH testing is recommended to support or confirm chromosome aberrations or when inconclusive results are found.  References are included in the report to help the referring physician with interpretation, which include books or journals that contain appropriate information.