Summary & Overview
CPT 0315U: DecisionDx–SCC Gene Expression Risk Stratification
CPT code 0315U identifies DecisionDx®–SCC, a proprietary RT–PCR gene expression profiling test for squamous cell carcinoma (SCC) that classifies metastatic risk into Class 1 (low), Class 2A (moderate), and Class 2B (high). As a PLA code tied to a single manufacturer's assay, 0315U is used when FFPE tissue from an SCC lesion is analyzed in a clinical laboratory setting. Nationally, PLA codes like 0315U matter because they link clinical decision tools directly to unique commercial tests, affecting coding clarity, claims processing, and policy decisions for molecular diagnostics.
Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise orientation to the clinical application of the test, typical sites of service, payer coverage landscape, and the types of benchmarks and policy issues that commonly arise with PLA molecular diagnostics. The publication summarizes coverage considerations, common billing modifiers, and operational notes relevant to laboratories and billing professionals. Data not supplied in the input—such as specific payer policy details, associated taxonomies, ICD‑10 diagnoses mapping, and related codes—is noted as unavailable and therefore not included in the analysis.
Billing Code Overview
CPT code 0315U is a Proprietary Laboratory Analyses (PLA) code for DecisionDx®–SCC, a genomic test manufactured by Castle Biosciences, Inc. The assay uses formalin–fixed paraffin–embedded (FFPE) tissue from a skin lesion diagnosed as squamous cell carcinoma (SCC) and applies reverse–transcription polymerase chain reaction (RT–PCR) gene expression profiling to measure activity of 40 genes (34 content genes and 6 housekeeping genes). An algorithmic analysis of the gene expression data stratifies metastatic risk into Class 1 (low risk), Class 2A (moderate risk), and Class 2B (high risk).
Service type: Proprietary laboratory molecular diagnostic test (gene expression profiling)
Typical site of service: Clinical laboratory or hospital outpatient laboratory using FFPE tissue specimens
Clinical & Coding Specifications
Clinical Context
A typical patient is an adult who presents to a dermatology clinic with a biopsy-confirmed cutaneous squamous cell carcinoma (SCC). The surgical dermatologist or dermatopathologist prepares formalin-fixed paraffin-embedded (FFPE) tissue from the diagnostic biopsy or from the excision specimen and submits the block or unstained slides to Castle Biosciences, Inc. for DecisionDx®–SCC testing. The test uses reverse-transcription polymerase chain reaction (RT–PCR) to measure expression of 34 content genes and 6 housekeeping genes and reports a risk category for metastasis as Class 1 (low risk), Class 2A (moderate risk), or Class 2B (high risk).
Typical clinical workflow: the treating clinician documents the SCC diagnosis and rationale for molecular prognostic testing (for example, high-risk tumor features or uncertainty about management). The pathology laboratory prepares and ships the FFPE material with required documentation and billing information. The laboratory or ordering clinician reports the DecisionDx–SCC result to the treating provider; the result informs risk stratification and multidisciplinary management discussions (surveillance intensity, imaging, adjuvant therapy consideration, or surgical margins). Billing uses PLA code 0315U for the proprietary Castle Biosciences assay, with appropriate specimen and service site indicated (commonly outpatient dermatology clinic, hospital outpatient department, or independent pathology lab).
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional component | Use when billing only the professional interpretation component separate from the technical laboratory processing when applicable and allowed. |
TC | Technical component | Use when billing only the technical component (laboratory processing) of the test. |
62 | Two surgeons | Use when two qualified providers share active surgical management and documentation supports distinct operative roles; relevant if billing providers coordinate specimen submission and surgical procedures. |
78 | Unplanned return to OR following initial procedure | Use when an unplanned return to the operating room related to the initial procedure leads to additional specimen submission tied to this assay. |
80 | Assistant surgeon | Use when an assistant surgeon performed part of the operative procedure and is billing for services related to specimen procurement. |
82 | Assistant surgeon (when qualified assistant unavailable) | Use when a qualified assistant is not available and an assistant bills for services related to specimen procurement. |
55 | Work split (postoperative care only) | Use when the billing provider is only furnishing postoperative management while another provider billed for the test or procedure. |
52 | Reduced services | Use when the submitted specimen or service is limited or partial relative to the full test (e.g., inadequate tissue leading to limited analysis) and payer allows modifier for reduced service. |
53 | Discontinued service | Use when the procedure was started but discontinued and specimen submission/billing reflects the discontinued status. |
QX | Ordering physician services furnished under a contract (modifier identifying the assistant) | Use when specimen procurement or related services are furnished under a contractual arrangement requiring identification of the performing clinician. |
| Taxonomy Code | Specialty | Notes |
|---|---|---|
| 207N00000X | Dermatology | Dermatologists commonly order DecisionDx–SCC after biopsy or excision for risk stratification. |
| 207P00000X | Dermatopathology | Dermatopathologists perform diagnostic interpretation and prepare FFPE tissue for molecular testing. |
| 207K00000X | General Surgery | Surgical oncologists or general surgeons may be involved when excisions or reconstructions are performed and specimens submitted. |
| 363L00000X | Laboratory–Molecular Genetic Testing | Molecular pathology laboratories perform RT–PCR and analytic reporting of the PLA test. |
| 207Q00000X | Otolaryngology (ENT) | ENT surgeons may order testing for SCC of the head and neck skin sites when relevant to management. |
Related Diagnoses
| ICD-10 Code | Description | Clinical Relevance |
|---|---|---|
C44.221 | Basal cell carcinoma of skin of face | Although this code is for basal cell carcinoma, it is listed here to indicate differential diagnoses encountered in dermatologic practice; DecisionDx–SCC is specific to squamous cell carcinoma and would not be used for BCC. |
C44.112 | Squamous cell carcinoma of skin of eyelid | SCC at periorbital or facial sites where risk stratification with DecisionDx–SCC may inform management due to high-risk anatomic location. |
C44.92 | Squamous cell carcinoma of skin, unspecified | Used when SCC is diagnosed and the anatomic site is not specified in coding; DecisionDx–SCC applies to SCC specimens for metastasis risk assessment. |
C44.31 | Squamous cell carcinoma of skin of scalp and neck | SCC at scalp/neck sites where prognostic molecular testing may influence surveillance and treatment planning. |
C44.519 | Squamous cell carcinoma of skin of unspecified ear and external auricular canal | SCC of ear sites that often carry higher risk and where DecisionDx–SCC testing may be considered. |
Related CPT Codes
| CPT Code | Description | Relationship to This Procedure |
|---|---|---|
88305 | Level IV surgical pathology, gross and microscopic examination | Often billed by the pathology lab to report the initial diagnostic microscopic evaluation of the skin biopsy or excision that establishes SCC and provides tissue for 0315U. |
88342 | Immunohistochemistry, per single antibody stain | May be used for ancillary immunostains performed on the FFPE tissue as part of the diagnostic workup prior to or alongside molecular testing. |
88331 | Consultation and review of slides prepared elsewhere (pathology consult) | Used when a dermatopathologist or pathologist performs a consultation review of slides to confirm diagnosis and suitability of tissue for molecular testing. |
88313 | Special stains, other than immunohistochemistry, per specimen | Used for special histochemical stains that may be part of the pathology evaluation before molecular testing. |
83890 | Molecular pathology procedure, Level I (example nucleic acid amplification) — Note: placeholder for molecular procedures | Represents molecular laboratory processes; laboratories performing DecisionDx–SCC use PLA code 0315U rather than additive molecular CPTs for the proprietary assay. |