Exc back les sc 3 cm/>

CPT code 21931 covers the surgical removal of a lesion, mass, or abnormal growth from beneath the skin on the back when it measures 3 centimeters (about 1.2 inches) or larger. This is a more complex excision that involves cutting through skin layers to remove the deeper growth and typically requires closure with stitches.

Showing rates for

National Average

Base Medicare rate

$464.82

This calculator gives a typical-case estimate using standard Medicare modifier rules. Actual payment depends on payer policies, documentation, code-specific CMS status indicators, and locality. Verify before billing.

RVU breakdown

Work RVU

6.88

PE RVU (NF)

5.85

MP RVU

1.64

Total RVU

14.37

Conversion factor: 32.3465 · Source: CMS MPFS RVU25A · Confidence: High

NCCI bundling edits

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Billing tips

Document the exact measured size of the excised lesion in the operative report, measured after excision and confirmed by pathology specimen dimensions. Size determines code selection (21930 vs 21931 vs 21932).
Impact: Incorrect size documentation can result in downcoding from 21931 ($464.82) to 21930 (smaller lesion code with lower reimbursement), representing potential loss of $100-200 per procedure
Clearly document the anatomical location as 'back' and the tissue depth as 'subcutaneous' to distinguish from skin tag removals, shave biopsies, or deeper fascial excisions which use different code families.
Impact: Prevents denials for incorrect anatomical coding and supports medical necessity; lack of location specificity leads to 15-25% initial denial rate
Submit pathology report with the claim or have it readily available for audit, as payers frequently request this to verify lesion type, size, and depth, especially for higher-value codes.
Impact: Proactive pathology submission reduces payment delays by 30-45 days and decreases audit-related recoupments
When billing multiple excisions, sequence codes correctly with the highest RVU procedure first (without modifier 51) and append modifier 51 to subsequent procedures to maximize reimbursement.
Impact: Proper sequencing can save $50-150 per claim when multiple procedures are performed; incorrect sequencing triggers automatic reimbursement reductions
Verify that the excised lesion is truly subcutaneous and not intramuscular or subfascial, as those require different CPT codes (21935-21936) with different reimbursement rates.
Impact: Using incorrect depth-based codes leads to 20-30% denial rate and potential audit flags for pattern coding errors

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Frequently asked questions

What is the Medicare reimbursement rate for CPT 21931 in 2025?

The 2025 Medicare national average reimbursement rate for CPT 21931 is $464.82 for both facility and non-facility settings. This rate is based on 14.37 total RVUs (6.88 work RVU, 5.85 practice expense RVU, and 1.64 malpractice RVU) multiplied by the 2025 conversion factor of 32.3465. Actual reimbursement varies by geographic location based on locality adjustments.

What is the difference between CPT 21930 and 21931?

The primary difference is lesion size. CPT 21930 is used for excision of subcutaneous soft tissue tumors on the back that are less than 3 centimeters in diameter, while CPT 21931 is for lesions 3 centimeters or greater. The size threshold directly impacts reimbursement, with 21931 having higher RVUs and payment due to increased complexity and operative time required for larger lesions.

Can CPT 21931 be billed with an E/M code on the same day?

Yes, but only with modifier 25 appended to the E/M code, and only if there is a separately identifiable evaluation and management service beyond the normal pre-operative assessment for the excision. The E/M must be for a distinct problem or represent significant additional work. Many payers scrutinize same-day E/M billing with surgical procedures, so documentation must clearly support the separate service.

Does CPT 21931 include wound closure or is that coded separately?

Simple layered closure is included in CPT 21931 and should not be coded separately. However, if the closure requires complex reconstruction, skin grafts, or flap procedures beyond simple layered closure due to defect size or location, these may be separately billable using appropriate closure codes (such as adjacent tissue transfer codes 14000-14302). Documentation must clearly indicate why closure was complex and not routine.

What documentation is needed to support medical necessity for CPT 21931?

Medical necessity documentation should include: clinical symptoms (pain, limitation of movement, bleeding, infection), duration and growth pattern of the lesion, clinical concern for malignancy based on examination or imaging characteristics, functional impairment, failure of conservative management if applicable, and patient history factors increasing risk. Pre-operative imaging or photographs supporting size and characteristics strengthen medical necessity justification.

How many times can CPT 21931 be billed in one operative session?

CPT 21931 can be billed multiple times if multiple distinct subcutaneous lesions measuring 3cm or greater are excised from the back during the same session. The first excision is billed without modifier 51, and subsequent excisions are billed with modifier 51 appended, typically receiving 50% reimbursement. Each lesion must be separately documented with individual size, location, and pathology. Some payers limit the number of excisions reimbursed per session.

What is the global period for CPT 21931?

CPT 21931 has a 90-day global surgical period. This means routine post-operative care including wound checks, suture removal, and typical follow-up visits within 90 days of the procedure are included in the surgical fee and cannot be billed separately. Complications, unrelated E/M services (with modifier 24), or staged procedures (with modifier 58) may be separately billable during the global period with appropriate documentation and modifiers.