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Interpretive Handbook

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Test 19499:
Leukemia/Lymphoma Immunophenotyping by Flow Cytometry, Tissue

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

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.

Useful For Suggests clinical disorders or settings where the test may be helpful

Evaluation of tissues for potential involvement by a lymphoproliferative disorder or acute leukemia

Interpretation Provides information to assist in interpretation of the test results

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 CD2, CD3, CD5, and CD7. Typically, no appreciable blast population is present.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

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. Cases in which the viability is <20% will be considered inadequate for evaluation. Cerebrospinal fluid (CSF), fine needle aspiration, and small biopsy specimens have a higher frequency of rejection due to low cell counts and/or poor viability from these sources.

 

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.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

An interpretive report will be provided.

Clinical References Provides recommendations for further in-depth reading of a clinical nature

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