Summary & Overview
CPT 0058U: Merkel SmT Oncoprotein Antibody Titer
CPT code 0058U designates the Merkel SmT Oncoprotein Antibody Titer, a Proprietary Laboratory Analyses (PLA) test performed by the University of Washington’s Department of Laboratory Medicine to detect and quantify antibodies to the Merkel cell polyomavirus small T antigen. The assay targets a tumor-specific oncoprotein relevant to Merkel cell carcinoma (MCC), a rare but highly aggressive neuroendocrine skin cancer; as a PLA, the code applies only to this specific test and provider.
This national-level summary highlights coverage and policy relevance for major payers, with Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare included in the overview. The publication describes clinical context for use in MCC surveillance and diagnosis, summarizes typical sites of service and service type, and outlines what readers will find in the full report: payer coverage benchmarks, coding and billing considerations, and clinical context for interpretation.
Readers will learn where CPT code 0058U fits in laboratory service lines, how PLA status affects coding and billing, and the practical implications for hospital and outpatient laboratory operations. Data not available in the input is noted where specific payer coverage determinations, reimbursement rates, and associated taxonomies or ICD-10 linkage are not provided.
Billing Code Overview
CPT code 0058U is a Proprietary Laboratory Analyses (PLA) code for the Merkel SmT Oncoprotein Antibody Titer developed by the University of Washington’s Department of Laboratory Medicine. The test detects and quantifies antibodies to the Merkel cell (MC) polyomavirus small T (sT) antigen/oncoprotein, a key oncogenic driver implicated in Merkel cell carcinoma (MCC), an aggressive neuroendocrine skin cancer.
Service Type: Laboratory diagnostic serology — proprietary antibody quantification
Typical Site of Service: Clinical laboratory or hospital laboratory setting; sample collection commonly performed in outpatient phlebotomy or hospital outpatient drawing stations.
Clinical & Coding Specifications
Clinical Context
A 68-year-old patient with a history of a rapidly growing, firm, painless cutaneous nodule on the forearm is diagnosed with Merkel cell carcinoma (MCC) by biopsy. The treating dermatologic oncologist orders the Merkel SmT Oncoprotein Antibody Titer performed by the University of Washington Department of Laboratory Medicine to detect and quantify antibodies to the Merkel cell polyomavirus small T (sT) antigen. The test is used as a tumor-associated serologic marker to aid in baseline staging, to help assess tumor burden, and to monitor disease recurrence or response during surveillance after definitive therapy (surgery, radiation, or systemic therapy).
Typical clinical workflow:
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Patient evaluated in dermatology or oncology clinic; biopsy confirms MCC.
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Order placed for proprietary laboratory test
0058Uwith clinical indication of MCC and intent (baseline serology or surveillance). -
Blood draw performed in outpatient phlebotomy or oncology infusion center; specimen shipped per University of Washington instructions.
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Laboratory performs proprietary assay and reports quantitative sT antibody titer; result is returned to ordering clinician and placed in the medical record.
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Clinician interprets titer in the context of imaging, pathology, and clinical exam to inform surveillance intervals and assessment of treatment response.