Summary & Overview
CPT 88361: Immunohistochemistry with Computer-Assisted Cell Enumeration
CPT code 88361 covers a pathology workflow combining a single antibody immunostain with computer-assisted cell counting and pathologist interpretation. The service supports diagnostic precision in specimens such as tumor tissue by pairing automated enumeration with expert pathological review, which can influence diagnostic classification, prognostic assessment, and treatment planning. Nationally, this code represents an intersection of digital pathology, laboratory automation, and traditional anatomic pathology practice.
Key payers examined include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find an overview of how 88361 is defined clinically, common billing considerations, and where this service typically occurs (clinical laboratories and hospital pathology departments). The publication also outlines benchmarking context and relevant policy considerations affecting coverage and coding practices for immunohistochemistry services that rely on computer-assisted image analysis.
This analysis provides clinicians, billing professionals, and policy stakeholders with a concise reference on the clinical role of 88361, payer coverage landscape, and practical coding context to inform billing and administrative workflows. Data not available in the input is noted where applicable.
Billing Code Overview
CPT code 88361 describes a pathology service in which a laboratory analyst applies a single antibody immunostain to slide(s) prepared from a single patient specimen (for example, tumor tissue). The slides are processed using computer-assisted technology that counts or estimates the number of stained cells. A qualified provider, typically a pathologist, reviews the stained slides and the computer-generated enumeration and interprets the results to render a pathologic diagnosis.
Service type: Immunohistochemistry with computer-assisted cell enumeration and pathologist interpretation
Typical site of service: Clinical laboratory or hospital pathology department, where tissue specimens and stained slides are prepared and reviewed.
Clinical & Coding Specifications
Clinical Context
A 62-year-old patient with a recently biopsied breast mass undergoes immunohistochemical testing to determine hormone receptor status and proliferative index. The laboratory receives formalin-fixed paraffin-embedded tumor tissue from the surgical pathology accession. A histology technologist prepares slides and applies a single antibody stain (for example, estrogen receptor or Ki-67) to the slides from this single patient specimen. The slides are processed using computer-assisted image analysis that enumerates stained cells and calculates a percentage of positive tumor nuclei. A board-certified pathologist reviews the stained slides, reviews the computer-generated cell counts and images, integrates morphologic features and staining patterns, and issues a pathology report with interpretation (e.g., receptor positive/negative, percentage positive) to guide oncology treatment planning.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional component | Use when reporting only the pathologist's interpretation and report, separate from the technical processing of staining. |
TC | Technical component | Use when billing only for the laboratory technical work (slide staining and image analysis) without the professional interpretation. |