CurrentPremera BluecrossPolicy ROUTINE TEST MANAGEMENT POLICY - 15.01.005

ROUTINE TEST MANAGEMENT POLICY - 15.01.005 Immunohistochemistry

Governs reimbursement and procedural coding rules for immunohistochemistry testing and provides background, definitions, and quality/validation guidance affecting laboratories and payees submitting claims to Premera Bluecross.

Policy Summary

PayerPremera Bluecross

PolicyROUTINE TEST MANAGEMENT POLICY - 15.01.005 Immunohistochemistry

Policy CodePolicy ROUTINE TEST MANAGEMENT POLICY - 15.01.005

Change TypeNo material change

Effective DateFeb 6, 2026

Next Review Date

Key ActionUse CPT 88342 for the initial single antibody per specimen (1 unit/specimen, up to 4 specimens/day); use 88341 for each additional single antibody and 88344 for multiplex antibodies as described.

SourceLink

POLICY UPDATE CHANGES

No material clinical or coverage changes in this revision.

88342: 1/unit up to 4initial single antibody reimbursable limit

88341: up to 13additional single antibody max

88344: up to 6multiplex antibody limit

≥90%CAP validation concordance

10/20/40+validation sample minima

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Coverage Criteria & Laboratory Quality Requirements

Coverage criteria and laboratory validation requirements

IHC testing is reimbursable per this routine test management policy; laboratories must validate and verify assays consistent with CAP recommendations and document decisions when fewer samples are used.

ALL of the following

Immunohistochemistry testing is reimbursable as outlined in this policy; coverage and reimbursement are subject to member benefit plan limits and this policy does not apply to Medicare Advantage.
ALL of the following
- For laboratory-developed assays with predictive or nonpredictive applications using the same scoring criteria, treat as predictive: minimum 20 positive and 20 negative cases.
- Perform separate validations for IHC on cytologic specimens with different fixation; recommended minimum 10 positive and 10 negative cases when possible; increase numbers if validating predictive markers or document rationale if infeasible.
ALL of the following
- Confirm with at least 1 known positive and 1 known negative tissue before placing into clinical service.
- When dilution, vendor (same clone), or incubation/retrieval times change, confirm with at least 2 known positive and 2 known negative tissues.
The laboratory medical director determines how many predictive and nonpredictive markers and how many positive and negative tissues to test when fixative, antigen retrieval, detection system, processing equipment, platform, or environmental conditions change; document rationale when fewer than recommended cases are used.
A full revalidation equivalent to initial analytic validation is required when the antibody clone is changed for an existing validated assay.

IHC CPT Codes, Limits, and Coding Details

IHC CPT codes and descriptionsCPTCovered

88342	Immunohistochemistry or immunocytochemistry, per spec; initial single antibody stain.
88341	Immunohistochemistry or immunocytochemistry, per specimen; each additional single antibody stain procedure
88344	Immunohistochemistry or immunocytochemistry, per specimen; each multiplex antibody stain procedure.

88342 specimen limit

88342 specimen limitInitial single antibody: reimbursable at 1 unit per specimen, up to 4 specimens per date of service.

Billing useUse CPT 88342 for the first single antibody procedure per specimen.

ScopeApplies per date of service; counting is by specimen up to the 4‑specimen limit.

88341 unit maximum

88341 unit maximumEach additional single antibody per specimen: reimbursable up to a maximum of 13 units per date of service.

Billing useReport CPT 88341 for each additional single antibody stain procedure beyond the initial 88342.

Billing, Prior Authorization, and Provider Guidance

Billing Rule

IHC CPT billing rules and unit limits

Use CPT 88342 for the first single-antibody stain per specimen (reimbursable at 1 unit per specimen, up to 4 specimens per date of service). Use CPT 88341 for each additional single-antibody stain per specimen (reimbursable up to a maximum of 13 units per date of service). Use CPT 88344 for each multiplex antibody stain per specimen (reimbursable up to six specimens per date of service).

First single antibody per specimen: CPT 88342 — 1 unit/specimen, up to 4 specimens per date of service
Each additional single antibody per specimen: CPT 88341 — up to 13 units per date of service
Each multiplex antibody per specimen: CPT 88344 — reimbursable up to 6 specimens per date of service

Note

Reimbursement scope and member benefit limits

Immunohistochemistry testing is reimbursable as outlined in this policy; coverage and reimbursement are subject to the limits and conditions of the member benefit plan and this policy does not apply to Medicare Advantage.

Terms and Acronyms

Immunohistochemistry (IHC)

DefinitionImmunohistochemistry (IHC) is a sensitive and specific staining technique that uses antibodies and a biochemical tag or label to identify cells, tissues, and organisms by interaction with target antigens.

PurposeUsed to detect target antigens in tissue via monoclonal antibodies and visualization methods.

MethodCombines anatomical, biochemical, and immunological methods for antigen–antibody detection.

mIHC (multiplex immunohistochemistry)

mIHC definitionMultiplex immunohistochemistry (mIHC) allows multiple targets in a single tissue to be detected simultaneously, enabling characterization of the tumor microenvironment and immune cell quantitation.

Terminology linkage

Policy Summary

PayerPremera Bluecross

PolicyROUTINE TEST MANAGEMENT POLICY - 15.01.005 Immunohistochemistry

Policy CodePolicy ROUTINE TEST MANAGEMENT POLICY - 15.01.005

Change TypeNo material change

Effective DateFeb 6, 2026

Next Review Date

SourceLink

On This Page

AggregationThe 13‑unit maximum is calculated per date of service across specimens as applicable.

88344 specimen limit

88344 specimen limitEach multiplex antibody per specimen: reimbursable up to six specimens per date of service.

Billing useUse CPT 88344 to report multiplex immunohistochemistry procedures performed on a specimen.

Specimen countingLimit is specified as specimens per date of service (up to 6).

Consult the member benefit booklet or contact member services to determine applicable benefit limitations.
This policy is a guide to clinical appropriateness and reimbursement methodology and may be updated as appropriate.

mIHC is listed as a defined term in the policy terminology tables (mIHC = Multiplex immunohistochemistry).

Use caseUsed when simultaneous detection of several markers on a single specimen is required.

Terminology and marker abbreviations

IHC acronymIHC = Immunohistochemistry (defined in terminology table).

Common marker abbreviationsExamples include AFP (alpha‑fetoprotein), CD markers (e.g., CD1a, CD5, CD10), Bcl2, BRCA1, and many others listed in the Table of Terminology.

Other acronymsmIHC = Multiplex immunohistochemistry; ISH = In situ hybridization; LDTs = Laboratory‑developed tests; CAP = College of American Pathologists.

Laboratory‑developed test (LDT)

LDT definitionLaboratory‑developed tests (LDTs) are high‑complexity tests regulated by CMS under CLIA '88 and are not approved or cleared by the FDA for clinical use.

Regulatory framingLDTs are performed and validated in‑house by laboratories and fall under CLIA '88 oversight rather than FDA clearance for routine clinical use.

Contextual noteFDA clearance or approval is not currently required for clinical use of LDTs, though some IHC assays have been validated and used in trials and may receive regulatory recognition.

HER2 testing guidance (ASCO/CAP)

ASCO/CAP recommendationASCO and CAP recommend that all newly diagnosed breast cancer patients have HER2 testing performed; test metastatic site tissue when available.

ISH and IHC interpretationDual‑probe ISH is preferentially recommended; in certain less common ISH result groups, concomitant IHC review is required to determine final HER2 status.

2018 updates2018 guidance revised IHC 2+ definition and emphasized more rigorous interpretation criteria for uncommon ISH patterns; recommendations were reaffirmed in 2023.

Single‑probe ISH guidanceLaboratories using single‑probe ISH assays should include concomitant IHC review as part of interpretation of single‑probe ISH results.