Test ID: LLPT    
Leukemia/Lymphoma Immunophenotyping, Flow Cytometry, Tissue

Evaluation of tissues for potential involvement by:

-Chronic lymphoproliferative disorders

-Malignant lymphomas

-Acute lymphoblastic leukemia

-Acute myelogenous leukemia

When this test is ordered, a screening panel and a professional interpretation will always be charged. The screening panel will be charged based on number of makers tested (FIRST for first marker, ADD1 for each additional marker). The interpretation will be set based on markers tested in increments of 9 to 15, or 16 and greater. In addition, reflex testing may occur to fully characterize a disease state or clarify any abnormalities from the screening test. Reflex tests will be performed at an additional charge for each marker tested (FIRST if applicable, ADD1 if applicable).

The tissue panel is initially performed to evaluate for monotypic B-cells by kappa and lambda light chain expression, and increased numbers of blasts and plasma cells by CD45 expression along with side scatter gating. The panel can also evaluate T cells with CD3, CD5, and CD7. Additionally, viability is assessed on all tissue specimens using 7-AAD exclusion.

This panel, together with the provided clinical history and morphologic review, is used to determine what, if any, further testing is needed for disease diagnosis or classification. If additional testing is required, it will be added per algorithm to fully characterize a disease state with a charge per unique antibody tested.

In addition to reflexing flow cytometric panels, fluorescence in situ hybridization (FISH) or molecular testing may be recommended by the Mayo pathologist to facilitate diagnosis. They will contact the referring physician or pathologist to confirm the addition of these tests.

Cellular immunophenotyping, characterizing cells by using antibodies directed against cell surface markers, is generally regarded as a fundamental element in establishing a diagnosis of tissue involvement by hematolymphoid malignancies, when used in conjunction with morphologic assessment. It is also an essential component in subclassification of hematolymphoid malignancies, when present.

An interpretive report will be provided.

Normal tissues typically contain a mixture of B cells with polytypic surface immunoglobulin light chain expression and T cells with unremarkable expression of the T cell-associated antigens CD3, CD5, and CD7. Typically, no appreciable blast population is present by CD45 and side scatter analysis.

It is well recognized that a negative flow cytometry result does not exclude tissue involvement by hematolymphoid malignancy. This may be attributable to sampling bias, although some malignancies, such as Hodgkin lymphoma, are not detected by this technique.

Viability will be assessed in all tissue specimens. Cases in which the viability is low (<50%) are prone to false-negative results and, therefore, must be interpreted with caution. In cases with viability less than 30%, testing will be attempted but may not be interpretable. Fine-needle aspiration and small biopsy specimens have a higher frequency of low cell counts and poor viability, which may be uninterpretable.

Even when abnormal, in most instances the results of flow cytometry are insufficient for complete subclassification of a hematolymphoid malignancy. Precise subclassification requires correlation with the histopathologic features in paraffin-embedded materials and also, in some instances, the results of cytogenetic analyses.

The tissue used for flow cytometry cannot be subsequently submitted for histopathologic evaluation. For this reason, this technique should be avoided in small biopsy specimens.

1. Morice WG, Hodnefield JM, Kurtin PJ, Hanson CA: An unusual case of leukemic mantle cell lymphoma with a blastoid component showing loss of CD5 and aberrant expression of CD10. Am J Clin Pathol. 2004 July;122(1):122-127

2. Hanson CA: Acute leukemias and myelodysplastic syndromes. In: McClatchey KD, ed. Clinical Laboratory Medicine. Williams and Wilkins Inc;1994:939-969

3. Jaffe ES, Cossman J: Immunodiagnosis of lymphoid and mononuclear phagocytic neoplasms. In: Rose NR, Friedman H, Fahey JL, eds. Manual of Clinical Immunology. 3rd ed. ASM Press;  1987:779-790

4. Witzig TE, Banks PM, Stenson MJ, et al: Rapid immunotyping of B-cell non-Hodgkin's lymphomas by flow cytometry. Am J Clin Pathol. 1989;94:280-286

5. Jevremovic D, Dronca RS, Morice WG, et al: CD5+ B-cell lymphoproliferative disorders: Beyond chronic lymphocytic leukemia and mantle cell lymphoma. Leuk Res. 2010 Sep;34(9):1235-1238

6. Jevremovic D, Olteanu H: Flow cytometry applications in the diagnosis of T/NK-cell lymphoproliferative disorders. Cytometry B Clin Cytom. 2019 Mar;96(2):99-115

7. Shi M, Jevremovic D, Otteson GE, Timm MM, Olteanu H, Horna P: Single antibody detection of T-Cell receptor alpha beta clonality by flow cytometry rapidly identifies mature T-Cell neoplasms and monotypic small CD8-positive subsets of uncertain significance. Cytometry B Clin Cytom. 2020 Jan;98(1):99-107

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