Summary & Overview

CPT 0090U: myPath® Melanoma RT–PCR Gene Expression Profiling

CPT code 0090U designates the myPath® Melanoma proprietary laboratory test from Castle Biosciences Inc., a molecular diagnostic RT–PCR mRNA gene expression profiling assay that evaluates 23 genes in a biopsy specimen of a lesion suspicious for malignant melanoma and reports results as benign, intermediate, or malignant. This PLA code identifies a single manufacturer-specific test and matters nationally because it standardizes billing for a widely used genomic adjunct to histopathology in melanoma assessment.

Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. The publication summarizes national coverage and billing patterns for CPT code 0090U, highlighting where payers commonly apply medical necessity criteria, prior authorization, or coverage with evidence development for genomic tests.

Readers will learn the clinical context for using the myPath® Melanoma assay, typical sites of service, common billing modifiers, and how this PLA code fits into molecular pathology service lines. The report provides benchmarks and policy-relevant observations about payer handling of PLA codes, common documentation expectations for biopsy-based gene expression testing, and practical coding considerations for clinical laboratories and dermatology/pathology practices. Data not available in the input are noted where applicable.

AetnaBlue Cross Blue ShieldCigna HealthUnitedHealthcareMedicare0090UCPTProprietary Laboratory Analysesmolecular diagnosticsgene expression profilingmelanomadermatopathologylaboratory test

Billing Code Overview

CPT code 0090U is a Proprietary Laboratory Analyses (PLA) code for the myPath® Melanoma test produced by Castle Biosciences Inc. The test uses RT–PCR mRNA gene expression profiling to analyze a biopsy specimen of a lesion suspicious for malignant melanoma by evaluating expression of 23 genes. Results are reported as benign, intermediate, or malignant to assist in diagnostic classification.

Service Type: Molecular diagnostic assay / gene expression profiling

Typical Site of Service: Clinical laboratory processing of dermatopathology biopsy specimens

Clinical & Coding Specifications

Clinical Context

A 52-year-old patient presents to a dermatology clinic with a pigmented skin lesion that appeared irregular in shape and color change over several months. The dermatologist performs a diagnostic shave or excisional biopsy of the lesion under local anesthesia and submits the formalin-fixed tissue to an anatomic pathology laboratory. Histopathology returns an indeterminate result where conventional microscopy cannot definitively rule in or out malignant melanoma. The clinician orders the myPath® Melanoma test (Proprietary Laboratory Analyses code 0090U) to analyze mRNA expression of 23 genes using RT–PCR on the biopsy specimen. The laboratory performs RNA extraction, gene expression profiling, and reports a result categorized as benign, intermediate, or malignant. The report informs the treating clinician’s decision on need for wider excision, sentinel lymph node evaluation, or close surveillance. Typical sites of service include outpatient dermatology clinics, ambulatory surgical centers, and reference molecular pathology laboratories. Common patient factors include history of atypical/dysplastic nevi, prior melanoma, lesion on sun-exposed skin, or clinically suspicious changes prompting biopsy.

Coding Specifications

Modifier	Description	When to Use
`00`	Service provided and not otherwise specified

Taxonomy Code	Specialty	Notes
`207N00000X`	Dermatology	Dermatologists perform biopsy and order molecular testing
`207P00000X`	Dermatopathology	Dermatopathologists interpret histology and may coordinate molecular testing
`207L00000X`	Anatomic Pathology	Anatomic pathologists process specimens and order/send out molecular assays
`207RC0000X`	Molecular Genetic Pathology	Labs and specialists overseeing RT–PCR-based gene expression testing
`363A00000X`	Laboratory Medicine	Clinical laboratory directors responsible for test performance and reporting

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`D03.9`	Melanoma in situ, unspecified	Lesions suspicious for early melanoma may be evaluated with molecular profiling when histology is equivocal
`C43.9`	Malignant melanoma of skin, unspecified	Used when invasive melanoma is confirmed or strongly suspected and molecular results inform management
`L98.0`	Disorders of pigmentation	Pigmented lesions with atypical features can prompt biopsy and adjunct molecular testing
`R23.3`	Spontaneous ecchymoses	Pigmented or bruiselike skin changes occasionally require biopsy to exclude melanoma
`Z85.820`	Personal history of malignant melanoma of skin	Prior melanoma increases index of suspicion and may lower threshold for advanced testing
`L81.0`	Ephelides (freckles)	Differentiation of benign pigmented lesions from melanoma can involve molecular tests
`D22.9`	Melanocytic nevi, unspecified	Atypical nevi with borderline histology are common indications for adjunctive gene expression assays
`L57.0`	Actinic keratosis	Sun-damaged skin with lesions that mimic melanoma may lead to biopsy and subsequent molecular analysis

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`0090U`	myPath® Melanoma; RT–PCR mRNA gene expression profiling (23 genes) reported as benign, intermediate, or malignant	Primary PLA code for the molecular test performed on a biopsy specimen to aid melanoma diagnosis
`88305`	Level IV surgical pathology, gross and microscopic examination	Commonly reported for initial histopathologic evaluation of excised skin lesions before molecular testing
`88342`	Immunohistochemistry, per specimen; first single stain	Frequently used adjunct to histology to evaluate melanocytic markers prior to or alongside molecular testing
`84999`	Unlisted chemistry procedure	Occasionally used historically for novel or unique molecular assays prior to availability of PLA codes (now superseded by `0090U`)
`88313`	Special staining (e.g., melanocytic stains)	Used when additional histochemical stains are performed to characterize melanocytic lesions