IHC coding and unit limits — follow CPT and unit rules

Code and unit reimbursement rules for immunohistochemistry must be followed: use 88342 for the first single antibody procedure (reimbursed at one unit per specimen, up to four specimens per date of service), 88341 for each additional single antibody per specimen (reimbursed up to a maximum of 13 units per date of service), and 88344 for each multiplex antibody per specimen (up to six specimens per date of service).

• 88342: first single antibody per specimen — 1 unit/specimen, up to 4 specimens per date of service
• 88341: each additional single antibody per specimen — reimbursed up to 13 units per date of service
• 88344: each multiplex antibody per specimen — up to 6 specimens per date of service

Prior authorization status unchanged after literature review

Prior authorization and the policy's coverage criteria remain unchanged after the literature review; there were no modifications to prior authorization or coverage criteria documented during the update.

Provider documentation and billing preparedness

Ensure coding, documentation, and billing adhere to the policy limits and guidance above; retain specimen-level documentation to support units billed and readiness to supply plan-specific authorization if requested.

• Maintain specimen counts and antibody type documentation per specimen and date of service to support CPT code selection and units billed
• Be prepared to reference the plan contract (Evidence of Coverage) if authorization/payment conflicts arise

No step therapy requirements specified

No step therapy requirements are specified in the provided sections of this policy.

Coding and documentation requirements — use 88342 / 88341 / 88344 as specified

Use CPT code 88342 for the first single antibody stain per specimen, CPT 88341 for each additional single antibody stain per specimen, and CPT 88344 for each multiplex antibody stain per specimen; documentation should support specimen counts and antibody types per specimen and date of service.

• Document number of specimens and which antibody (single vs multiplex) was run on each specimen
• Code 88342 only once per specimen for the initial single antibody; additional single antibodies on that specimen use 88341

Revision history — evidence/guidelines updated without coverage changes

Revision history records updates to background, guidelines, and evidence-based references but did not change coverage criteria; note the 05/23/2022 update that refreshed evidence references.

• 01/01/2022: Initial Effective Date
• 05/23/2022: Updated background, guidelines, and evidence-based scientific references; literature review did not change coverage criteria

Reimbursement unit limits — overbilling may be denied

Billing beyond the stated reimbursement units (for example, more than four specimens billed under 88342 or more than 13 total units of 88341 per date of service) may trigger payment denial or adjustment and may require justification.

• Claims exceeding 88342 limits (greater than 1 unit per specimen or more than 4 specimens per date of service) may be denied or adjusted
• Claims exceeding 88341 total unit maximum (over 13 units per date of service) may be denied or adjusted

Literature review did not change coverage criteria (provider affirmation)

The literature review concluded that no modifications to the coverage criteria were necessary; providers may rely on existing coverage rules and coding limits as documented.

Coverage depends on member benefits at time of request

Coverage depends on the individual's benefit coverage at the time of request; the Medical Policy Statement does not guarantee authorization or payment and the plan contract (Evidence of Coverage) governs determinations.

• Verify member benefit coverage and Evidence of Coverage prior to ordering
• Policy statements do not ensure authorization or payment

Who may order testing not specified

The policy sections provided do not specify which provider types may order testing.