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    v1.0.31
    OpenPayerBilling CodesGenetic Analysis ProceduresCPT cpt-81342-tcell-receptor-gamma-clonality-assay
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    CPT 81342: T-Cell Receptor Gamma (TRG@) Clonality Assay

    CPT code 81342 describes a laboratory molecular diagnostic test for detection of abnormal clonal T‑cell populations by analysis of the T‑cell receptor gamma (TRG@) gene; service type: molecular pathology / diagnostic laboratory procedure; typical site of service: clinical laboratory or hospital laboratory performing the technical testing component.

    For related coverage guidance, see recent payer policy updates: Minimal Residual Disease (MRD) Testing for Cancer, Biomarker Testing Mandate, Prenatal (Fetal) Diagnostic Testing.

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    Clinical & Coding Specifications

    Clinical Context

    A 62-year-old male with progressive lymphadenopathy and unexplained cytopenias is referred to hematology after peripheral blood smear and flow cytometry suggest a T-cell lymphoproliferative disorder. A core needle biopsy of an enlarged lymph node and a peripheral blood specimen are submitted to the molecular laboratory for clonality testing. The laboratory performs a 81342 assay to detect clonal T‑cell receptor gamma (TRG@) gene rearrangements to help distinguish reactive T‑cell expansions from malignant clonal T‑cell populations. Results are integrated with histopathology, immunophenotyping, and clinical findings and reported to the ordering hematologist/oncologist.

    Typical workflow steps:

    • Specimen receipt and accessioning (lymph node tissue, bone marrow aspirate, or peripheral blood).

    • DNA extraction and quality assessment.

    • PCR amplification and fragment analysis or sequencing of TRG@ locus per validated laboratory protocol.

    • Interpretation for monoclonal versus polyclonal T‑cell populations and reporting of the technical result (81342) with correlation notes for the ordering clinician.

    Typical site of service: hospital clinical molecular pathology laboratory, independent reference molecular laboratory, or academic medical center molecular diagnostics lab.

    Related CPT Codes

    CPT CodeDescriptionRelationship to This Procedure
    87316Infectious agent antigen detection by enzyme immunoassay (EIA), qualitative or semiquantitativeOften ordered in differential infectious evaluations but not directly related to clonality testing; included here for institutions that bundle infectious workup.
    81275BCR-ABL1 (ABL1) gene analysisOther molecular tests frequently performed in suspected hematologic malignancies; complements TRG@ testing when differential includes B‑cell or myeloid neoplasms.
    81291JAK2 V617F mutation analysisCommon concurrent molecular test in marrow disorders; ordered alongside clonality testing in some myeloproliferative differential evaluations.
    81479Unlisted molecular pathology procedureUsed for novel or otherwise unlisted molecular tests that may accompany or complement 81342 when no specific CPT exists.
    88305Level IV surgical pathology, gross and microscopic examinationHistopathologic examination of lymph node or tissue biopsy performed prior to or alongside clonality testing; results are correlated with 81342 findings.

    If additional related CPT codes are required for billing bundles or panels, institutions map testing combinations per local policies and payor rules.

    Related Modifiers

    7 rows

    ModifierDescriptionWhen to Use
    26Modifier 26 (Professional Component) identifies and bills only the professional portion of a split service — the physician’s interpretation, report, and medical judgment — when the technical…- Use CPT Modifier -26 when you are billing only the professional component (PC) of a split‑bill eligible service—i.e., you performed the physician interpretation, medical judgment and prepared a…
    59Modifier 59 indicates a distinct procedural service when two procedures that are not normally billed together are clinically and procedurally separate. The CPT definition (as reiterated by CMS)…- Use modifier -59 to report a distinct procedural service when documentation supports that the procedure reported is not normally billed together with another service on the same day because of a…
    90Modifier ‑90 (Reference/Outside Laboratory) indicates that a laboratory test was performed by an entity other than the treating or reporting provider. The American Medical Association defines…- Use CPT modifier -90 when a laboratory test is performed by an outside/reference laboratory (an entity other than the treating or reporting physician or qualified professional) and the claim needs…
    91Modifier 91 — “Repeat Clinical Diagnostic Laboratory Test” — is appended when the exact same CPT laboratory test is performed more than once for the same patient on the same day because serial,…- Use modifier 91 when the exact same CPT laboratory test is performed more than once on the same patient on the same date because serial or repeated testing is medically necessary to monitor…
    52Modifier ‑52 (Reduced Services) indicates that a service or procedure was partially reduced or omitted at the provider’s discretion, allowing reporting of the basic procedure number with a qualifier…- Use modifier -52 when a physician or qualified health professional electively reduces or omits part of a procedure or service (for example, performing fewer required views or omitting a portion of…
    53Modifier 53 (Discontinued Procedure) signals that a surgical or diagnostic service was begun by the physician but terminated because of extenuating circumstances that threatened the patient’s…- Use modifier -53 when a physician/qualified healthcare professional has started a surgical or diagnostic procedure (e.g., anesthesia administered, incision or scope insertion) and then discontinues…
    62Modifier 62 indicates that two surgeons function as co‑surgeons, each performing distinct parts of the same primary surgical procedure. It is appended to the primary procedure code (and any…- Use modifier -62 when two surgeons act as co‑surgeons (both primary surgeons) on a single definitive primary procedure, each performing distinct parts of the same surgical procedure (append -62 to…

    Related Provider Taxonomies

    8 rows

    Taxonomy Code
    207R00000X
    208000000X
    207L00000X
    207K00000X
    237700000X
    225C00000X
    163WX0002X
    156F00000X

    Related Payer Policy Updates

    Specialty: Genetic & Molecular Testing1 / 3

    10 rows

    PolicyPayerEffective Date
    Minimal Residual Disease (MRD) Testing for Cancerregence2027-01-01
    Biomarker Testing MandateBlue Cross Blue Shield - Rhode Island2027-01-01
    Prenatal (Fetal) Diagnostic TestingBlue Cross Blue Shield - Rhode Island2027-01-01
    Oral Cancer Screening and TestingOscar Health2027-01-01
    RTM Testing for Alpha-1 Antitrypsin DeficiencyOscar Health2027-01-01
    Cytochrome P450 Genotype-Guided Treatment Strategy Corporate Medical Policybcbsvermont2027-01-01
    Polygenic Risk ScoreBlue Cross Blue Shield - Rhode Island2026-12-01
    Gene Expression Profiling for Cutaneous MelanomaBlue Cross Blue Shield - Rhode Island2026-12-01
    Genetic Testing for Macular Degenerationregence2026-11-01
    Pharmacogenetic Panel Testing (for Ohio Only)Colorado Rocky Mountain Health Plans2026-11-01

    Related Codes

    CPT-81105-HPA-1-PLATELET-ANTIGEN-1-GENOTYPING-ITGB3-CD61

    CPT 81105: HPA-1 (ITGB3/CD61) Genotyping, Technical Component

    CPT-81106-HPA-2-T145M-GENETIC-ALLELE-ANALYSIS

    CPT 81106: HPA-2 (T145M) Platelet Antigen Genotyping

    CPT-81107-HPA-3-GENETIC-ANALYSIS-TECHNICAL-COMPONENT

    CPT 81107: HPA‑3 (I843S) Platelet Antigen Genotyping

    CPT-81108-HPA-4-R143Q-GENOTYPING

    CPT 81108: HPA-4 (R143Q) Genotyping

    CPT-81109-HPA-5-K505E-GENETIC-ANALYSIS

    CPT 81109: HPA-5 (K505E) Genotyping Test

    CPT-81110-HPA-6-R489Q-GENOTYPING

    CPT 81110: HPA-6 (R489Q) Genotyping, Technical Component

    CPT-81111-HPA-9-V837M-ALLELE-ANALYSIS

    CPT 81111: HPA-9 (V837M) Genotyping, Technical Test

    CPT-81112-HPA-15-GENETIC-ANALYSIS-S682Y

    CPT 81112: HPA-15 (S682Y) Platelet Antigen Genotyping

    CPT-81120-IDH1-MOLECULAR-DIAGNOSTIC-TEST

    CPT 81120: IDH1 Mutation Detection, Technical Component

    CPT-81121-IDH2-MOLECULAR-DIAGNOSTIC-TEST

    CPT 81121: IDH2 Mutation Detection, Technical Component

    Showing 1–10 of 199

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    Frequently Asked Questions

    References

    1. 1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
    2. 2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
    3. 3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.
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