CurrentHealthfirstPolicy PO-RE-038v5

Immunohistochemistry (IHC) coding and reimbursement

Defines coding, unit reimbursement, specimen limits, and billing instructions for immunohistochemistry (IHC) procedures (CPT codes 88341, 88342, 88344) and provides clinical background and guideline references; applies when benefit coverage permits and subject to Medicare/Medicaid rules.

Policy Summary

PayerHealthfirst

PolicyImmunohistochemistry (IHC) coding and reimbursement

Policy CodePolicy PO-RE-038v5

Change TypeClarified (background/guidelines updated)

Effective DateNov 15, 2015

Next Review Date

Key ActionReport 88342 for the initial single antibody stain per specimen (one unit per specimen), 88341 for each additional single antibody stain per specimen, and 88344 for each multiplex antibody stain per specimen.

SourceLink

POLICY UPDATE CHANGES

12/03/2025 revision updated background, guidelines, and references but did not change coverage criteria.

3Primary CPT codes referenced

4Max 88342 specimens per date of service

13Max 88341 units per date of service

6Max 88344 specimens per date of service

Policy overview & scope

Trek Health ingests and normalizes Transparency in Coverage data and payer policy updates to give provider organizations a clear view of how commercial reimbursement behaves across markets, payers, and services. Our platform transforms raw payer disclosures into structured intelligence that supports contract evaluation, payer negotiations, and service line strategy. By combining market benchmarks with ongoing policy visibility, Trek helps teams identify variability, risk, and opportunity in commercial reimbursement. The result is faster insight, stronger negotiating positions, and more informed financial decisions.

Background: Immunohistochemistry (IHC) is a staining technique that uses antibodies to identify cells, tissues, and organisms by interaction of target antigens with specific antibodies visualized via a biochemical tag. IHC is applied for tumor identification and classification, selection of therapy (for example HER2 testing in breast cancer), and identification of infectious organisms; assays may be performed as single-antibody stains or as multiplex immunohistochemistry (mIHC) that detects multiple targets simultaneously and can characterize the tumor microenvironment. Panels of antibodies are emphasized over single-marker approaches because single markers are rarely entirely sensitive and specific; panels reduce risk of misclassification. The policy references analytic validation guidance and recommendations from professional organizations including the College of American Pathologists (CAP), the ASCO/CAP HER2 testing guidance, the National Comprehensive Cancer Network (NCCN), and the European Society for Medical Oncology (ESMO).

Scope summary: Defines coding, unit reimbursement, specimen limits, and billing instructions for immunohistochemistry (IHC) procedures (CPT codes 88341, 88342, 88344) and provides clinical background and guideline references; applies when benefit coverage permits and subject to Medicare/Medicaid rules.

Status and dates: Policy PO-RE-038v5 is CURRENT. Effective date: 11/15/2015; Last approval/last review date: 03/16/2026.

Policy metadata

Policy numberPO-RE-038v5

Policy title/subjectImmunohistochemistry (IHC) coding and reimbursement

PayerHealthfirst

Effective date11/15/2015

Last review03/16/2026

Next review

StatusCURRENT

Billing & reimbursement rules

Billing and Reimbursement Rules

Use the following CPT codes and unit limits per specimen and per date of service:

ALL of the following

Code 88342 - initial single antibody: Code 88342 is used for the first single antibody procedure and is reimbursed at one unit per specimen, up to four specimens, per date of service.<= 4 specimens per date of service
Reimbursed at one unit per specimen; do not bill more than four units of 88342 per date of service across specimens.
Code 88341 - additional single antibody: Code 88341 is used for each additional single antibody per specimen and is reimbursed up to a maximum of 13 units per date of service.<= 13 units per date of service
Do not bill more than 13 units of 88341 per date of service.
Code 88344 - multiplex antibody: Code 88344 is used for each multiplex antibody per specimen, up to six specimens, per date of service.<= 6 specimens per date of service
Do not bill more than six specimens billed with 88344 per date of service.

Thresholds

Max 88342 specimens / DOS<= 4 specimens

Max 88341 units / DOS<= 13 units

Max 88344 specimens / DOS<= 6 specimens

Billing, documentation, and operational guidance

Billing Rule

Use correct CPT code per antibody/stain

Report 88342 for the initial single antibody stain per specimen (one unit per specimen), 88341 for each additional single antibody stain per specimen, and 88344 for each multiplex antibody stain per specimen.

88342 — initial single antibody stain (first single antibody procedure, one unit per specimen)
88341 — additional single antibody stain (each additional single antibody per specimen)
88344 — multiplex antibody stain (each multiplex antibody stain per specimen)

Billing Rule

Adhere to specimen and unit limits per date of service

Do not bill more than four units of 88342 per date of service across specimens, do not bill more than 13 units of 88341 per date of service, and do not bill more than six specimens billed with 88344 per date of service.

Max 4 units of 88342 per date of service (across specimens)
Max 13 units of 88341 per date of service
Max 6 specimens billed with 88344 per date of service

Documentation Required

Coverage dependent on member benefits and regulatory rules

Confirm individual benefit coverage and applicable Medicare/Medicaid regulations prior to billing; reimbursement decisions are subject to the member's evidence of coverage, state/federal mandates, and participation agreements.

Confirm benefit coverage with the member's plan before billing
Verify applicable Medicare and Medicaid rules and any state mandates

Guidelines & evidence notes

Evidence and background: A literature review was completed and the policy record shows that on 12/03/2025 the background, guidelines, and references were updated; the literature review did not require modifications to coverage or coding criteria. The policy cites updated analytic validation guidance for IHC assays and specifies CAP recommendations for initial analytic validation and verification (including concordance thresholds and minimum numbers of positive and negative tissues for validation), ASCO/CAP guidance for HER2 testing and interpretation, NCCN recommendations endorsing CAP/ASCO guidance for breast and other cancers, and ESMO guidance for use of IHC in cancers of unknown primary.

Background summary: CAP guideline updates emphasize that laboratories must analytically validate laboratory-developed IHC assays and verify FDA-cleared assays, with recommended concordance of at least 90% overall between new assays and comparators and minimum validation sample sizes (e.g., 10 positive and 10 negative for many nonpredictive assays, and 20 positive and 20 negative for predictive marker assays), along with additional verification steps for changes in antibody lot, clone, vendor, or testing conditions. The policy references ASCO/CAP HER2 testing guidance (including concomitant IHC review with ISH in certain cases), NCCN recommendations for tumor testing (including IHC/MSI for colorectal cancer screening), and ESMO statements on IHC for cancers of unknown primary.

Policy changes & review timeline

2015-11-15effective_date

Policy effective date (Immunohistochemistry reimbursement and coding rules)

2025-12-03literature_review

Literature review updated; no modifications to coverage/coding criteria

2026-03-16last_reviewLatest

Most recent policy review/approval date

Policy Summary

PayerHealthfirst

PolicyImmunohistochemistry (IHC) coding and reimbursement

Policy CodePolicy PO-RE-038v5

Change TypeClarified (background/guidelines updated)

Effective DateNov 15, 2015

Next Review Date

SourceLink

On This Page

OpenPayer

Immunohistochemistry (IHC) coding and reimbursement

Policy overview & scope

Billing & reimbursement rules

Applicable CPT codes

Billing, documentation, and operational guidance

Key terms

Guidelines & evidence notes

Policy changes & review timeline

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