Summary & Overview
CPT 88374: Multiplex In Situ Hybridization with Pathologist Interpretation
CPT code 88374 represents a pathology laboratory service for a single multiplex in situ hybridization (ISH) probe stain processed with computer-assisted enumeration and interpreted by a qualified provider, typically a pathologist. This advanced diagnostic assay supports tumor characterization and can influence treatment selection and prognosis, making it a nationally relevant code as precision oncology testing expands.
Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of clinical context, common sites of service, and typical laboratory workflow tied to the code. The publication outlines reimbursement benchmarks, billing considerations, and recent policy updates affecting coverage and coding practice for ISH testing, where available. It also highlights operational implications for laboratories, including requirements for computer-assisted enumeration and documentation of pathologist interpretation.
This summary serves clinicians, laboratory managers, and billing professionals seeking a national-level briefing on the clinical role and administrative handling of CPT code 88374 in modern pathology services.
Billing Code Overview
CPT code 88374 describes a laboratory pathology service in which a lab analyst performs a single multiplex in situ hybridization (ISH) probe stain on slide(s) prepared from a single patient specimen, such as tumor tissue. The process uses computer-assisted technology to count or estimate probe signals. A qualified provider, typically a pathologist, reviews the stained slides together with the computer-generated enumeration and interprets the findings to render a pathologic diagnosis.
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Service type: Pathology laboratory diagnostic testing involving multiplex in situ hybridization with computer-assisted enumeration and pathologist interpretation.
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Typical site of service: Hospital or independent pathology laboratory (histopathology/oncology diagnostic lab) where tissue specimens and slide processing are performed.
Clinical & Coding Specifications
Clinical Context
A 62-year-old patient with a recently biopsied breast mass is undergoing molecular testing to determine HER2 gene copy number and amplification status. The surgical pathology lab receives formalin-fixed, paraffin-embedded tumor tissue sections and prepares slides. A histology technologist or laboratory analyst applies a single multiplex in situ hybridization (ISH) probe stain to the slides (88374) and runs the stained slides through computer-assisted image analysis to count or estimate probe signals. A board-certified pathologist reviews the stained slides, evaluates the computer-assisted enumeration, integrates morphologic findings, and issues a final pathology report with interpretation of gene amplification status to guide targeted therapy decisions. Typical site of service is a hospital-based or independent clinical pathology laboratory affiliated with an outpatient oncology clinic or inpatient hospital. The service type is diagnostic molecular pathology testing performed on tissue (cytogenetic/molecular ISH) with both a technical component (slide preparation, staining, image analysis) and a professional component (pathologist interpretation). Typical scenario includes pre-treatment biomarker assessment for cancer management and therapeutic selection.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional component | Use when billing only the pathologist's interpretation and report for when technical component is billed separately. |