CPT 88342Laboratory

Imhchem/imcytchm 1st antb

CPT code 88342 is used when a laboratory performs immunohistochemistry or immunocytochemistry testing on tissue or cell samples, using the first antibody stain to help identify specific proteins or markers that assist in diagnosing diseases like cancer.

Showing rates for

National Average

Base Medicare rate

$109.01

This calculator gives a typical-case estimate using standard Medicare modifier rules. Actual payment depends on payer policies, documentation, code-specific CMS status indicators, and locality. Verify before billing.

RVU breakdown

Work RVU

0.7

PE RVU (NF)

2.65

MP RVU

0.02

Total RVU

3.37

Conversion factor: 32.3465 · Source: CMS MPFS RVU25A · Confidence: High

NCCI bundling edits

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Billing tips

Always bill 88342 for the first antibody stain only; use add-on code 88341 for each additional antibody on the same specimen block or slide
Impact: Prevents downcoding or denials; 88341 pays approximately $18-25 per additional stain versus the base $109.01 for 88342
Link IHC stains to specific ICD-10 diagnosis codes that justify medical necessity, such as neoplasm codes (C00-D49) or codes indicating diagnostic uncertainty (R codes)
Impact: Reduces denials by 30-40% when proper medical necessity is documented; many payers require pre-authorization for more than 5-6 stains per case
Document the specific antibody used and the clinical reason for each stain in the pathology report; generic descriptions like 'IHC panel' are insufficient
Impact: Audit-proof documentation prevents recoupment; MAC audits commonly target IHC for specificity, with average recoupment of $800-1,200 per case when documentation fails
Verify that control slides (positive and negative) are documented for each antibody run, as this is a CAP and CLIA requirement
Impact: Missing control documentation can result in denial of entire IHC claim; also creates regulatory compliance risk during laboratory inspections
Do not bill 88342 with 88341 on different date lines for the same case; all stains from a single block should be billed on the same date of service
Impact: Prevents duplicate payment issues and audit flags; some payers automatically deny when they detect split billing patterns
When billing both tissue preparation codes (88305, 88307) and IHC codes, ensure the diagnostic reasoning for immunostains is clearly documented in the final report

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Frequently asked questions

What is the difference between CPT 88342 and 88341?

CPT 88342 is used for the first immunohistochemistry or immunocytochemistry antibody stain performed on a specimen, reimbursed at $109.01 by Medicare in 2025. CPT 88341 is an add-on code used for each additional antibody stain performed on the same specimen block or slide, with lower reimbursement. You must always bill one unit of 88342 first, then add units of 88341 for subsequent stains.

How much does Medicare pay for CPT code 88342 in 2025?

Medicare pays $109.01 for CPT 88342 in 2025 based on the national average non-facility rate. This amount is calculated using the total RVU of 3.37 multiplied by the 2025 conversion factor of 32.3465. Both facility and non-facility rates are the same at $109.01 for this laboratory code.

How many IHC stains can I bill per specimen?

There is no absolute Medicare limit on the number of IHC stains per specimen, but medical necessity must be documented for each antibody used. Most payers consider 5-8 stains per case reasonable for complex diagnoses. Exceeding 10-12 stains often triggers prior authorization requirements or medical review. Each stain must be justified by the differential diagnosis and documented with specific clinical reasoning in the pathology report.

Can I bill 88342 with surgical pathology codes like 88305 or 88307?

Yes, CPT 88342 is separately billable from surgical pathology examination codes (88305, 88307, etc.). Immunohistochemistry represents additional diagnostic work beyond routine H&E examination and is not bundled with surgical pathology codes according to CMS guidelines and NCCI edits. Both services should be billed when performed, with appropriate diagnosis codes supporting the medical necessity of immunostains.

What documentation is required to bill CPT 88342?

Required documentation includes: the specific antibody name or clone used, clinical indication justifying the stain, positive and negative control results, interpretation of staining pattern (intensity, distribution, percentage), and integration into the final diagnosis. The pathology report must be signed by the interpreting pathologist and clearly show how the IHC results contributed to the diagnostic conclusion.

Does CPT 88342 require a modifier for Medicare billing?

CPT 88342 does not routinely require a modifier for standard Medicare billing when the complete service is performed and billed by one entity. Modifier 26 (professional component) or TC (technical component) is used only when splitting billing between the pathologist and laboratory. Modifier 59 or its X-variants may be needed in rare circumstances to indicate distinct services, but should be used cautiously to avoid audit triggers.

What are the RVUs for CPT code 88342 in 2025?

For 2025, CPT 88342 has a work RVU of 0.7, practice expense RVU of 2.65 (both facility and non-facility), and malpractice RVU of 0.02, for a total RVU of 3.37. These values are from the CMS Medicare Physician Fee Schedule RVU25A file released December 23, 2024.