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Test Code TLBLF T-Lymphoblastic Leukemia/Lymphoma, FISH, Tissue

Shipping Instructions

Advise Express Mail or equivalent if not on courier service.

Necessary Information

Provide a reason for referral and pathology report with each specimen. The laboratory will not reject testing if this information is not provided, but appropriate testing and interpretation may be compromised or delayed.

Specimen Required

Submit only 1 of the following specimens:

Specimen Type: Tissue

Container/Tube: Formalin-fixed, paraffin-embedded tumor tissue block


Specimen Type: Slides

Specimen Volume: 4 Consecutive, unstained, 5 micron-thick sections placed on positively charged slides and 1 hematoxylin and eosin-stained slide


If not ordering electronically, complete, print, and send a Hematopathology/Cytogenetics Test Request Form (T726) with the specimen


Secondary ID


Useful For

Detecting a neoplastic clone associated with the common chromosome abnormalities seen in patients with T-cell lymphoblastic leukemia or lymphoma

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
_I300 Interphases, >=100 No No
_I099 Interphases, 25-99 No No
_IL25 Interphases, <25 No No
_PB03 Probe, +3 No No
_PB02 Probe, +2 No No
_PADD Probe, +1 No No
_PBCT Probe, +2 No No

Testing Algorithm

This test may be ordered in 2 distinct ways allowing different combinations of probes to be utilized based on the clinical question, including the standard (diagnostic) TLBL FISH panel and the individual TLBL FISH probes (per client request).


The specific TLBL FISH panel or probes requested must be noted on the request form or in the reason for referral. If no specific panel or FISH probes are indicated, the standard (diagnostic) panel will be performed.


The standard (diagnostic) panel includes testing for the following abnormalities, using the FISH probes listed:

-1p33 rearrangements, TAL1/STIL(SIL)

-t(5;14)(q35;q32), TLX3(HOX11L2)/BCL11B

-7q34 rearrangements, TRB(TCR beta)

-9p-, CDKN2A(p16)/D9Z1

-t(9;22)(q34;q11.2), ABL1 amplification, ABL1(ABL)/BCR

-t(10;11)(p12;q14), MLLT10(AF10)/PICALM

-11q23 rearrangements, MLL

-14q11.2 rearrangements, TRAD (TCR alpha delta)

-17p-, TP53/D17Z1


When an MLL rearrangement is identified, reflex testing will be performed with 1 or more dual-fusion probe sets (D-FISH) in an attempt to identify the translocation partner. Probes include:

-t(4;11)(q21;q23), AFF1(AF4)/MLL

-t(6;11)(q27;q23), MLLT4(AF6)/MLL

-t(9;11)(p22;q23), MLLT3(AF9)/MLL

-t(10;11)(p12;q23), MLLT10(AF10)/MLL

-t(11;19)(q23;p13.1), MLL/ELL

-t(11;19)(q23;p13.3), MLL/MLLT1(ENL)


When an TRB(TCR beta) rearrangement is identified, reflex testing will be performed with a dual-fusion probe sets
(D-FISH) in an attempt to identify the translocation partner.

-t(7;10)(q34;q24), TRB(TCR beta)/TLX1(HOX11)


When an TRAD(TCR alpha delta) rearrangement is identified, reflex testing will be performed with a dual-fusion probe sets
(D-FISH) in an attempt to identify the translocation partner.

-t(10;14)(q24;q11.2), TLX1(HOX11)/TRAD(TCR alpha delta)


This test includes a charge for application of the first probe set (2 FISH probes) and professional interpretation of results. Additional charges will be incurred for all reflex probes performed. Analysis charges will be incurred based on the number of cells analyzed per probe set. If no cells are available for analysis, no analysis charges will be incurred.

Method Name

Fluorescence In Situ Hybridization (FISH)

Reporting Name

T-Lymphoblastic Leuk/Lymph, FISH,Ts

Specimen Type


Specimen Minimum Volume

Formalin-fixed paraffin-embedded tissue block or for each probe set ordered, 1 unstained consecutive tissue sections cut at 5 microns and placed on positively charged microscope slides. Include 1 hematoxylin and eosin (H and E) stained slide.

Specimen Stability Information

Specimen Type Temperature Time
Tissue Ambient (preferred)

Reject Due To

No specimen should be rejected.

Clinical Information

T-lymphoblastic lymphoma (T-LBL) is the non-leukemic form of T-acute lymphoblastic leukemia (T-ALL). In the United States, the incidence of ALL is roughly 6,000 new cases per year (as of 2009), or approximately 1 in 50,000. ALL accounts for approximately 70 percent of all childhood leukemia cases (ages 0 to 19 years), making it the most common type of childhood cancer. Approximately 85% of pediatric ALL cases are B-cell lineage (B-ALL) and 15% are T-cell lineage (T-ALL). T-ALL is more common in adolescents than younger children and accounts for 25% of adult ALL. When occurring as a primary lymphoblastic lymphoma, approximately 90% are T-cell lineage versus only 10% B-cell lineage. T-LBL characteristically presents in adolescents and young adults as a mediastinal mass with or without concurrent bone marrow involvement. It is not uncommon that the only sample available with T-LBL involvement is a paraffin-embedded mediastinal or lymph node biopsy specimen.


Specific genetic abnormalities can be identified in the majority of T-ALL/LBL cases, although many of the classic abnormalities are “cryptic” by conventional chromosome studies and must be identified by fluorescence in situ hybridization (FISH) studies. Each of the genetic subgroups are important to detect and can be critical prognostic markers. One predictive marker, amplification of the ABL1 gene region, has been identified in 5% of T-ALL, and these patients may be responsive to targeted tyrosine kinase inhibitors. A combination of cytogenetic and FISH testing is currently recommended in all pediatric and adult patients to characterize the T-ALL/LBL clone for prognostic genetic subgroups.

Reference Values

An interpretive report will be provided.


A positive result is detected when the percent of cells with an abnormality exceeds the normal cutoff for the probe set.


A positive result is not diagnostic for T-lymphoblastic lymphoma (T-LBL), but may provide relevant prognostic information.


The absence of an abnormal clone does not rule out the presence of neoplastic disorder.

Clinical Reference

1. Graux C, Cools J, Michaux L, et al: Cytogenetics and molecular genetics of T-cell acute lymphoblastic leukemia: from thymocyte to lymphoblast. Leukemia 2006;20:1496-1510

2. Swerdlow SH, Campo E, Stefano PA, et al: The 2016 revision of the World Health Organization classification of lymphoid neoplasms. Blood 2016;127(20):2375-2390

3. van Grotel M, Meijerink JP, Beverloo HB, et al: The outcome of molecular-cytogenetic subgroups in pediatric T-cell acute lymphoblastic leukemia: a retrospective study of patients treated according to DCOG or COALL protocols. Haematologica 2006;91:1212-1221

4. World Health Organization Classification of Tumours of Haematopoietic and Lymphoid Tissues. Edited by SH Swerdlow, E Campo, NL Harris, et al. Lyon, IARC Press, 2017

Day(s) and Time(s) Performed

Samples processed Monday through Sunday. Results reported Monday through Friday, 8 a.m.-5 p.m.

Analytic Time

7 days

Performing Laboratory

Mayo Medical Laboratories in Rochester

Test Classification

This test was developed using an analyte specific reagent. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

88271 x 2, 88291-DNA probe, each (first probe set), Interpretation and report

88271 x 2-DNA probe, each; each additional probe set (if appropriate)

88271-DNA probe, each; coverage for sets containing 3 probes (if appropriate)

88271 x 2-DNA probe, each; coverage for sets containing 4 probes (if appropriate)

88271 x 3-DNA probe, each; coverage for sets containing 5 probes (if appropriate)

88274 w/modifier 52-Interphase in situ hybridization, <25 cells, each probe set (if appropriate)

88274-Interphase in situ hybridization, 25 to 99 cells, each probe set (if appropriate)

88275-Interphase in situ hybridization, 100 to 300 cells, each probe set (if appropriate)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
TLBLF T-Lymphoblastic Leuk/Lymph, FISH,Ts In Process


Result ID Test Result Name Result LOINC Value
113467 Result Summary 50397-9
113468 Interpretation In Process
113626 Result Table In Process
113469 Result In Process
GC005 Reason for Referral 42349-1
113470 Specimen In Process
113471 Source In Process
113472 Tissue ID In Process
113473 Method In Process
113474 Additional Information 48767-8
113475 Disclaimer 62364-5
113476 Released By In Process