Summary & Overview
CPT 88364: In Situ Hybridization Single-Probe Stain and Interpretation
CPT code 88364 covers an add-on pathology procedure in which an additional in situ hybridization (ISH) single-probe stain is applied to slide(s) from the same patient specimen and qualitatively interpreted by a qualified provider, typically a pathologist. This service is used in situations such as tumor tissue evaluation when further single-probe ISH staining is required to clarify diagnostic or prognostic markers. Nationally, accurate coding and interpretation of ISH procedures are important for pathology workflows, clinical decision-making, and laboratory billing consistency.
Key payers in the analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find an overview of clinical context for the service, common payers that cover the code, and the types of benchmarks and policy considerations typically associated with laboratory pathology add-on services. The publication provides clarity on where this service is typically performed (hospital or independent pathology laboratories), the role of the laboratory analyst and the interpreting pathologist, and typical use cases such as additional testing on tumor specimens.
Data not available in the input for some fields. The content focuses on national implications, payer coverage profiles, and the clinical and billing context that informs use of CPT code 88364.
Billing Code Overview
CPT code 88364 describes a pathology service in which a laboratory analyst performs an additional in situ hybridization (ISH) single-probe stain on slide(s) prepared from the same patient specimen as an initial probe stain. A qualified provider, typically a pathologist, then performs a qualitative interpretation of the stained slide(s) to provide a pathologic diagnosis.
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Service type: Pathology technical and interpretive add-on for single-probe ISH performed on previously prepared patient slides
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Typical site of service: Hospital pathology laboratory, independent or hospital-based reference laboratory, or other clinical laboratory settings where tissue specimens (for example, tumor tissue) are processed and interpreted
Clinical & Coding Specifications
Clinical Context
A 62-year-old patient with a previously diagnosed breast mass undergoes a core needle biopsy. The initial in situ hybridization (ISH) single probe stain, such as HER2, is performed on the tumor tissue and yields an indeterminate or borderline result. The laboratory technologist applies an additional single probe ISH stain on a new slide prepared from the same biopsy specimen. A board-certified pathologist reviews the additional stained slide(s), qualitatively interprets signal patterns, and issues a pathologic report to determine receptor status and guide targeted therapy decisions.
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Service Type: Diagnostic pathology—molecular cytogenetic testing (additional ISH single probe stain and interpretation).
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Typical Site of Service: Hospital pathology laboratory, independent reference laboratory, or outpatient surgical pathology laboratory associated with a hospital or cancer center.
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Typical Patient Scenario: Patient with suspected or confirmed malignancy (e.g., breast carcinoma) where initial ISH single probe testing is inconclusive, equivocal, or requires repeat/confirmatory testing to establish biomarker status for treatment planning.
Coding Specifications
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