Summary & Overview
HCPCS G0461: Immunohistochemistry / Immunocytochemistry, First Antibody Stain
HCPCS Level II code G0461 covers the first single or multiplex immunohistochemistry (IHC) or immunocytochemistry (ICC) stain performed on a specimen. IHC/ICC stains are integral to modern diagnostic pathology—informing cancer subtyping, identifying infectious agents, and guiding targeted therapy decisions. Nationally, clear coding for these assays affects laboratory workflow, claims processing, and aggregate utilization measurement across hospital and independent laboratories.
Key payers included in this analysis are Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of what G0461 denotes clinically and operationally, expectations for typical sites of service, and which payers commonly reimburse for these pathology services. The piece outlines common modifiers and lists gaps where input data was not provided.
The publication provides benchmarks and contextual policy notes relevant to lab billing and reimbursement for pathology procedures, explains the service line placement for IHC/ICC staining, and summarizes implications for coding consistency and claims adjudication. Data not available in the input is explicitly noted where relevant.
Billing Code Overview
HCPCS Level II code G0461 represents immunohistochemistry or immunocytochemistry, per specimen; first single or multiplex antibody stain. This service involves applying antibody-based stains to tissue or cellular specimens to detect specific antigens, aiding pathological diagnosis and characterization of disease.
Service type: Diagnostic laboratory / pathology procedure
Typical site of service: Hospital pathology laboratory, independent or hospital-affiliated diagnostic laboratory, or specialized anatomic pathology lab
Data not available in the input.
Clinical & Coding Specifications
Clinical Context
A surgical pathology laboratory receives a formalin-fixed paraffin-embedded tissue block from a breast core needle biopsy. The pathologist reviews routine hematoxylin and eosin (H&E) slides and requests an immunohistochemistry (IHC) panel to subtype a suspected invasive carcinoma and to determine receptor status. A histology technician performs antigen retrieval and staining on an automated stainer. A single immunohistochemical stain (first antibody) such as estrogen receptor (ER) or cytokeratin AE1/AE3 is applied to one slide; the laboratory documents the reagent lot, staining protocol, and controls. The pathologist interprets the stain and issues a report that includes the IHC result, diagnosis, and a correlation with H&E morphology. Billing uses G0461 for the first single or multiplex antibody stain per specimen; modifier 26 is used if only the professional (interpretive) component is billed, and modifier TC is used if only the technical (laboratory) component is billed. Typical site of service is an independent or hospital-based pathology laboratory or hospital outpatient department. A common patient scenario is evaluation of a new breast mass in a 58-year-old female with imaging suspicious for malignancy (e.g., ICD-10 C50.912 used clinically to indicate a suspected primary breast cancer at time of pathology processing).
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional component | Use when billing only the pathologist's interpretation/reporting for the IHC stain separate from the laboratory technical work |
TC | Technical component | Use when billing only the laboratory's performance of the stain, including reagents and instrumentation |
59 | Distinct procedural service | Use when a separate, distinct service or procedure not normally billed together is performed on the same date |
76 | Repeat procedure by same provider | Use when the same IHC stain is repeated by the same provider on the same specimen/session |
77 | Repeat procedure by another provider | Use when the same IHC stain is repeated by a different provider or laboratory |
90 | Reference (outside) laboratory | Use when the IHC stain is performed by an outside/reference laboratory and only the test result is reported by the billing provider |
91 | Repeat clinical lab test (repeat within short timeframe) | Use when a quantitative/qualitative lab test is repeated within a short interval as defined by payer policy (rare for IHC) |
Q0 | Investigational clinical service paid under clinical trial | Use when IHC is performed as part of a qualifying clinical trial protocol (check payer trial requirements) |
Q2 | Service related to an approved clinical trial | Use when the IHC service is related to a trial with specific reimbursement rules |
XE | Separate encounter | Use when the technical or professional component is performed during a separate patient encounter from other services |
| Taxonomy Code | Specialty | Notes |
|---|---|---|
| 207P00000X | Anatomic and Clinical Pathology | Pathologists who interpret IHC and issue diagnostic reports |
| 207L00000X | Clinical Laboratory | Laboratory directors or medical technologists overseeing technical staining processes |
| 2080P0002X | Surgical Pathology | Surgical pathologists performing tissue diagnosis and ancillary testing |
| 207K00000X | Clinical Pathology | Clinicians involved in laboratory medicine oversight and quality control |
| 363LP0800X | Histotechnology | Histotechnologists who perform tissue processing and immunostaining in the lab |
Related Diagnoses
| ICD-10 Code | Description | Clinical Relevance |
|---|---|---|
C50.912 | Malignant neoplasm of unspecified site of right female breast | Common indication for IHC to subtype breast carcinoma and assess receptor status |
C50.911 | Malignant neoplasm of unspecified site of left female breast | Common indication for IHC to subtype breast carcinoma and assess receptor status |
D05.90 | Unspecified carcinoma in situ of unspecified breast | IHC may be used to clarify in situ versus invasive components and to support diagnosis |
C34.90 | Malignant neoplasm of unspecified part of unspecified bronchus or lung | IHC is frequently used to differentiate lung primary versus metastatic disease and subtype tumors |
C71.9 | Malignant neoplasm of brain, unspecified | IHC can help classify primary brain tumors and guide molecular testing decisions |
Related CPT Codes
| CPT Code | Description | Relationship to This Procedure |
|---|---|---|
88342 | Immunohistochemistry or immunocytochemistry, per specimen; first single or multiplex antibody stain | CPT 88342 is the CPT equivalent work description often used in professional coding for the interpretation component of a first IHC stain and parallels G0461 for Medicare outpatient/hospital settings |
88341 | Immunohistochemistry or immunocytochemistry, per specimen; initial single antibody stain, if using CPT pairings | 88341 may be reported in some private payer systems for single stains; it is related when multiple single stains are performed on a specimen |
88344 | Immunohistochemistry or immunocytochemistry, per specimen; additional single or multiplex antibody stain | Used when additional stains beyond the first are performed on the specimen in the same case |
88360 | Morphologic or metabolic multicolor staining, interpretation and report | Used for special staining techniques or multiplex panel interpretations that go beyond single-antibody stains |
88305 | Level IV surgical pathology, gross and microscopic examination | Often the primary surgical pathology CPT used for specimen evaluation; IHC (G0461/88342) is ordered in conjunction with the primary anatomic pathology service |