Summary & Overview
HCPCS M1166: Pathology Report for Wide Local Excision/Re-excision
HCPCS Level II code M1166 denotes a pathology report for tissue specimens produced from wide local excisions or re-excisions. This code captures the diagnostic pathology service that documents histologic findings after surgical removal of tissue, often used in oncologic and dermatologic contexts where margin assessment and specimen characterization are critical. Nationally, accurate coding of pathology reports supports clinical decision-making, continuity of care after surgery, and appropriate claims processing.
Key payers covered in this overview include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise outline of the clinical context for M1166, the typical settings where the service is delivered, and the operational role of the code in billing workflows. The publication also summarizes common modifiers associated with pathology and surgical specimen services, notes gaps where input data is unavailable, and highlights areas relevant to reimbursement benchmarking and claims adjudication.
The content provides a high-level resource for coding specialists, practice managers, and policy analysts who need to understand what M1166 represents, where it is used, and which major payers are relevant for coverage and payment considerations. Data not available in the input is clearly indicated where applicable.
Billing Code Overview
HCPCS Level II code M1166 describes a pathology report for tissue specimens produced from wide local excisions or re-excisions. This service typically represents the histopathologic examination and reporting of surgical specimens obtained during wide local excision or re-excision procedures.
Service type: Pathology / Anatomic Pathology
Typical site of service: Hospital outpatient pathology laboratory, hospital inpatient laboratory, or independent pathology laboratory associated with surgical procedures
Data not available in the input.
Clinical & Coding Specifications
Clinical Context
A 62-year-old patient with a history of cutaneous melanoma undergoes a wide local excision of a lesion on the upper arm to achieve clear margins. The surgeon removes the primary lesion with surrounding tissue and sends multiple tissue specimens, including peripheral and deep margin samples, to the pathology laboratory for histopathologic evaluation. The pathology team processes, sections, stains (including immunohistochemistry when indicated), examines the specimens microscopically, and issues a detailed pathology report documenting diagnosis, margin status, tumor thickness, ulceration, and any additional findings that affect staging and further management. The pathology report described by M1166 typically accompanies surgical procedures such as wide local excision or re-excision for neoplastic lesions and is used by surgical, dermatology, and oncology teams to guide adjuvant therapy and surveillance decisions.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
22 | Increased procedural services | Use when the pathology work required is substantially greater than typical (extensive additional sections, complex interpretation). |
23 |