Summary & Overview
CPT 17313: Mohs Micrographic Surgery, First Stage on Trunk/Extremities
Headline: CPT 17313: Mohs micrographic surgery (first stage, trunk/limbs) — scope and payer coverage
Lead: CPT 17313 defines the first-stage Mohs micrographic technique for lesions on the trunk, arms, or legs, including complete tumor removal, mapping, color coding, surgeon-performed microscopic examination, and histologic staining (up to five tissue blocks). This procedure is a cornerstone in skin cancer management when tissue-sparing margin control is essential.
What the code represents and national significance: CPT 17313 codifies the initial stage of Mohs surgery on the trunk and extremities, capturing both the surgical excision and intraoperative pathologic processing performed by the surgeon. Mohs surgery is a nationally recognized technique for high cure rates and tissue conservation in selected skin cancers, making accurate coding important for clinical documentation and payer reimbursement workflows.
Key payers covered: Major national payers include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Coverage and billing expectations commonly address site of service, documented clinical indication, and appropriate linkage to malignant skin neoplasm diagnoses.
Overview of reader takeaways: Readers will find an explanation of the clinical and procedural scope of CPT 17313, typical sites of service, common billing considerations, associated diagnosis codes for skin malignancies, related Mohs procedure codes for additional stages or blocks, and commonly applied modifiers. Data not available in the input will be noted where applicable.
CPT Code Overview
CPT 17313 describes Mohs micrographic technique for the trunk, arms, or legs (first stage, up to 5 tissue blocks). The procedure includes removal of all gross tumor, surgical excision of tissue specimens, mapping and color coding of specimens, microscopic examination of specimens by the surgeon, and histopathologic preparation with routine stains (for example, hematoxylin and eosin or toluidine blue). This is a dermatologic surgical procedure (Mohs micrographic surgery) typically performed in an outpatient facility or office setting (for example, POS 11 or POS 24).
Clinical & Coding Specifications
Clinical Context
A 68-year-old patient presents to a dermatology outpatient clinic with a biopsy-proven cutaneous malignancy on the right forearm. The procedure scheduled is Mohs micrographic surgery on the trunk, arms, or legs to achieve tissue-sparing complete margin control. The clinical workflow: pre-procedure evaluation and informed consent in the office; local anesthesia and excision of the visible tumor; surgeon maps, color-codes, and submits up to five tissue blocks for intraoperative microscopic examination with routine stains (eg, hematoxylin and eosin); if margins are positive, additional stages are performed and reported with appropriate add-on codes; defect reconstruction is completed during the same encounter or scheduled separately. Typical site of service is an outpatient facility or office (POS 11 or POS 24). Payors commonly involved include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, BUCA, and Medicare.
Coding Specifications
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Modifier
59: Distinct procedural service — used when Mohs micrographic surgery is performed on a separate lesion during the same day and must be reported separately from another procedure on the same date of service. -
Associated provider taxonomies:
| Taxonomy Code | Specialty |
|---|---|
207ND0900X | Dermatology |
207NS0135X | MOHS-Micrographic Surgery |
207N00000X | Dermatopathology |
Related Diagnoses
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C43.61— Malignant melanoma of right upper limb, including shoulderClinical relevance: A melanoma located on the upper limb may be treated with Mohs in select cases for margin control and tissue preservation when indicated.
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C43.62— Malignant melanoma of left upper limb, including shoulderClinical relevance: Same relevance as
C43.61for a lesion on the contralateral upper limb. -
C43.71— Malignant melanoma of right lower limb, including hipClinical relevance: Lower limb melanoma potentially managed with Mohs for margin assessment when appropriate.
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C43.72— Malignant melanoma of left lower limb, including hipClinical relevance: Same relevance as
C43.71for left lower limb lesions. -
C44.602— Unspecified malignant neoplasm of skin of right upper limb, including shoulderClinical relevance: Represents non-specified malignant skin tumors on the right upper limb that may be treated with Mohs for margin control.
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C44.609— Unspecified malignant neoplasm of skin of left upper limb, including shoulderClinical relevance: As above, for the left upper limb.
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C44.612— Basal cell carcinoma of skin of right upper limb, including shoulderClinical relevance: BCC on the upper limb is a common indication for Mohs micrographic surgery to ensure complete excision with tissue conservation.
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C44.619— Basal cell carcinoma of skin of left upper limb, including shoulderClinical relevance: Same relevance as
C44.612for the left side. -
C44.622— Squamous cell carcinoma of skin of right upper limb, including shoulderClinical relevance: SCC on the upper limb may be treated with Mohs when margin control is necessary, particularly for high-risk lesions.
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C44.629— Squamous cell carcinoma of skin of left upper limb, including shoulderClinical relevance: Same relevance as
C44.622for the left side. -
C44.702— Unspecified malignant neoplasm of skin of right lower limb, including hipClinical relevance: Unspecified malignant skin lesions of the right lower limb that may be candidates for Mohs.
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C44.709— Unspecified malignant neoplasm of skin of left lower limb, including hipClinical relevance: As above, for the left lower limb.
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C44.729— Squamous cell carcinoma of skin of left lower limb, including hipClinical relevance: SCC of the left lower limb that may warrant Mohs for margin control and tissue preservation.
Related CPT Codes
| CPT Code | Description | Relationship to 17313 |
|---|---|---|
17314 | Mohs micrographic technique … additional stages on trunk, arms, or legs | Reported when one or more additional Mohs stages are required beyond the first stage reported with 17313. Commonly used together during the same operative session if margins remain positive. |
17315 | Mohs micrographic surgery – additional blocks after first 5 blocks | Reported when more than five tissue blocks are submitted for the first stage; used as an add-on for additional blocks beyond the initial five included in 17313. Commonly used together with 17313 when the initial stage requires >5 blocks. |
National Reimbursement Benchmarks
Medicare's national mean allowed rate for CPT 17313 is $649.25, which sits below the BUCA (average commercial) mean of $678.22. This indicates that average commercial reimbursements represented by BUCA are modestly higher than Medicare at the national level for this code.
Dispersion varies notably across payers. Cigna shows one of the widest interquartile spreads (P75 − P25 = $465.50), followed by UnitedHealth Group (UHC) with a wide spread (P75 − P25 = $492.70). Aetna and Blue Cross Blue Shield (BCBS) exhibit tighter distributions (Aetna spread = $236.75; BCBS spread = $285.24). Medicare has the tightest interquartile range (P75 − P25 = $71.00). The table and chart below present the full breakdown.
State Benchmarks
State: AK1 / 50
Alaska Benchmarks
Alaska exhibits a substantial spread in reimbursement rates for CPT code 17313, with Blue Cross Blue Shield showing the widest range between the 25th and 75th percentiles ($684.33). This indicates significant variability in payment amounts among commercial payers, while Aetna's rates are notably consistent across percentiles. Compared to national averages, all commercial payers in Alaska reimburse at much higher rates, with Aetna's mean rate more than triple its national mean and UnitedHealth Group, BUCA, and Blue Cross Blue Shield also well above their respective national benchmarks.
The table and chart below present the full breakdown of mean rates and percentile values for each payer in Alaska, highlighting the differences in reimbursement levels and variability across the market.
Key Insights for Alaska
- Aetna is the highest paying payer in Alaska for CPT 17313, with a mean rate of $2,016.32, while Medicare is the lowest at $627.72.
- All commercial payers in Alaska reimburse at rates significantly above their respective national averages, with Aetna's mean rate more than triple the national mean.
- The rate spread (difference between 75th and 25th percentiles) is largest for Blue Cross Blue Shield, indicating greater variability in reimbursement compared to other payers.
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