Chromosome Analysis – Leukemic Blood

Test Overview

CPT Code(s)

88237, 88264, 88280, 88291

Methodology

Culture / Microscopy / Karyotype

Specimen Requirements

Container: Sodium Heparin (green top tube)

Optimal Quantity: 2-4 ml

Minimum Quantity: 1-2 ml

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

Clinical Significance

A chromosome analysis on leukemic blood may be clinically significant to identify and diagnose acquired neoplastic conditions associated with indications such as, cytopenias, T-cell lymphoma, B-cell lymphoma, multiple myeloma, acute myeloid leukemia, acute lymphocytic lymphoma, chronic myeloid leukemia, chronic lymphocytic leukemia, myeloprolypherative disorder and myelodysplastic syndrome.  It may also be relevant in cases to confirm or exclude the diagnosis of hematological malignancies based on morphology and track progress of treatment.

Clinical Background

Leukemic blood is studied for acquired abnormalities just the same as in bone marrows but is used instead of bone marrow in cases where there are confirmed circulating blasts in the blood or when it has become too difficult to attain a bone marrow sample from the patient.  In the hematologic malignant diseases, the recognized recurring chromosomal abnormalities often correlate with particular subtypes of leukemia that have characteristic morphologic and clinical features, such as response to therapy. One example of these abnormalities is the 15;17 translocation which is identified only in patients with promyelocytic leukemia. These consistent chromosomal aberrations acquired new significance with the localization of cellular transforming genes (oncogenes) to chromosome breakpoints that are involved in specific rearrangements. Thus, the study of chromosomal abnormalities in leukemia serves most importantly to assist in more accurate diagnosis and thereby providing prognostic information and allowing the more rational selection of therapy for patients. Chromosome analysis on leukemic blood serves as a diagnostic study for multiple 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

Leukemic blood 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 and karyotyping is carried out by two certified technologists using the Leica automated metaphase scanner and 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.