CPT Code 11644: Excision of malignant lesion, face, 3.1-4.0 cm

Key Takeaways

CPT Code 11644 describes excision of a malignant lesion including margins from the face, ears, eyelids, nose, or lips with an excised diameter of 3.1 to 4.0 cm.

Excised diameter includes the lesion plus all margins combined, not the lesion alone – mismeasurement is the most common reason for claim downcoding.

Simple repair is bundled into CPT 11644; only intermediate or complex repair codes may be separately billable, subject to current NCCI edits.

Pabau’s claims management software helps dermatology and surgical practices track excision measurements, link diagnosis codes, and reduce claim errors at the point of billing.

CPT Code 11644 covers excision of a malignant lesion, including margins, from the face, ears, eyelids, nose, or lips, with an excised diameter of 3.1 to 4.0 cm. Dermatology and surgical practices most often lose reimbursement on this code not from payer disputes, but from selecting the wrong code in the 11640-11646 series. The margin measurement step is where it goes wrong.

Dermatology billing software can flag measurement inconsistencies before submission, but coders still need a solid grasp of how 11644 works. This guide covers the official descriptor, diameter calculation, the full 11640-11646 comparison, modifiers, ICD-10 crosswalks, 2026 Medicare rates, RVU data, documentation requirements, and the most common billing errors.

CPT Code 11644: Definition and clinical description

Official CPT descriptor: Excision, malignant lesion including margins, face, ears, eyelids, nose, lips; excised diameter 3.1 to 4.0 cm.

CPT 11644 vs related codes: The 11640-11646 series

Six codes cover malignant lesion excision from the face, ears, eyelids, nose, and lips. The only variable separating them is the excised diameter. Getting this measurement wrong – even by a few millimeters – shifts the claim to the wrong code.

The boundary between 11643 and CPT Code 11644 is 3.0 cm. A lesion measuring exactly 3.0 cm excised diameter maps to 11643. Anything from 3.1 cm upward to 4.0 cm maps to CPT Code 11644. Coders billing surgical CPT codes across specialties encounter this boundary-measurement issue regularly across all size-tiered series.

The 11640-11646 series covers malignant lesions only. Benign lesion excision at the same facial sites follows a parallel diameter-tiering structure under 11423, while shaving a lesion without excising margins falls under 11310 instead.

How to measure excised diameter for CPT Code 11644

Excised diameter is not the lesion size alone. It is the total specimen diameter after excision, including the lesion and all surrounding margins. This distinction drives most downcoding errors in the 11640-11646 series.

According to AMA’s CPT code guidance, excised diameter is measured as the greatest single dimension of the specimen at the time of excision, not before margins are taken.

Worked example for CPT Code 11644 selection:

• Lesion greatest diameter: 2.4 cm
• Surgeon takes a 0.5 cm margin on each side
• Excised diameter: 2.4 cm + 0.5 cm + 0.5 cm = 3.4 cm
• 3.4 cm falls within the 3.1-4.0 cm range, so CPT Code 11644 applies
• If margins were only 0.3 cm each, excised diameter = 3.0 cm, and 11643 would apply instead

Document the calculation in the operative note. Payers auditing the claim will check that the stated excised diameter reflects lesion size plus margins, not just the lesion.

Modifiers for CPT Code 11644

Applying the correct modifier to CPT Code 11644 prevents payment reductions and avoids NCCI edit denials. The modifiers below are the most commonly used with this code, along with the clinical scenario that justifies each.

For broader CPT modifier guidance, the same documentation principles apply across surgical procedure families.

Modifier 50 (bilateral) is generally not appropriate for CPT Code 11644 because two separate lesions on bilateral sites are billed as two separate line items with RT and LT identifiers, not as a single bilateral code.

ICD-10 codes that support medical necessity for CPT Code 11644

Medicare and most commercial payers require a paired ICD-10-CM diagnosis code that confirms malignancy at the stated anatomical site. Coverage for CPT Code 11644 is governed by CMS LCD A57660, Medicare’s local coverage determination for excision of malignant skin lesions.

The table below covers the most frequently used ICD-10-CM codes paired with excision of malignant facial lesions.

Use the most specific code available. “Unspecified” codes (C43.30, C44.301) are acceptable when pathology has not yet confirmed the exact histological subtype, but they carry a higher audit risk than site-specific codes. Confirm with pathology before final billing where possible.

Coders selecting C55 or any other malignant neoplasm code across specialties follow the same specificity principle: Choose the most granular valid code for the documented clinical condition.

Medicare reimbursement and fee schedule for CPT Code 11644 (2026)

Medicare reimburses CPT Code 11644 at different rates depending on whether the procedure occurs in a facility (hospital outpatient, ambulatory surgical center) or a non-facility (physician office) setting. Non-facility rates are higher because the physician absorbs practice expense costs directly.

The rates below are national averages from the 2026 Medicare Physician Fee Schedule. Geographic adjustment factors (GPCI) modify actual payment by locality. Verify current rates using the CMS fee schedule tool for your specific MAC jurisdiction.

These figures are estimates based on publicly available MPFS data. Actual payment varies by locality, payer contract, and annual conversion factor updates. Always verify against the CMS CPT/HCPCS code list and current year fee schedule data before contract negotiations or budget projections.

RVU breakdown for CPT Code 11644

Relative Value Units determine Medicare payment under the Resource-Based Relative Value Scale (RBRVS). CMS finalized the CY2026 Medicare Physician Fee Schedule conversion factor at $33.5675 per RVU for qualifying Alternative Payment Model participants and $33.4009 per RVU for non-qualifying participants, effective January 1, 2026.

Work, practice expense, and malpractice RVU values are updated annually and can shift between code years, so verify current figures against the CMS fee schedule tool linked above before using them in contract negotiations or budget projections.

Reduce claim errors on excision procedures

Pabau's claims management tools help dermatology and surgical practices link diagnosis codes to procedures, flag measurement inconsistencies, and track payer-specific rules before submission.

Book a demo

Documentation requirements for billing CPT Code 11644

Medicare’s LCD A57660 and standard payer policy require specific documentation before CPT Code 11644 will be paid. Missing any element below triggers a documentation request or outright denial.

Maintaining HIPAA-compliant documentation workflows is especially important for surgical excision records, where operative notes and pathology reports constitute medical-legal documents as well as billing support. Good CPT documentation practices apply across procedure families: Record what was done, why, and how it was measured.

• Operative note: Must include the anatomical site, clinical description of the lesion, excised diameter measurement (lesion plus margins), margin dimensions, and the surgical technique used.
• Pathology report: Confirms malignancy. The report should identify the lesion type (melanoma, squamous cell carcinoma, basal cell carcinoma), site, and margin status. Without pathology confirmation, medical necessity is difficult to establish.
• Pre-operative diagnosis: The clinical indication documented before surgery must support the ICD-10-CM code billed. A lesion described only as “suspicious” without biopsy or clinical assessment may not satisfy medical necessity.
• Physician attestation: The operating physician must sign and date the operative note. A co-signature or dictated note not authenticated by the surgeon creates audit exposure.
• Place of service code: Determines which fee schedule applies (facility vs. non-facility). Mismatch between the place of service billed and where the procedure was actually performed is a common audit trigger.

Can repair codes be billed with CPT Code 11644?

Simple repair is bundled into CPT Code 11644. You cannot separately bill simple repair codes (12001-12021) alongside 11644. The AMA and NCCI treat simple wound closure as a component of the excision procedure itself.

Intermediate and complex repairs may be separately billable when the wound requires more than simple closure. The rules are specific:

• Simple repair (12001-12021): Bundled into 11644 by NCCI. Never separately billable.
• Intermediate repair (12031-12057): May be separately billed when the closure involves layered closure of deeper subcutaneous tissue. Requires documentation that the closure was not routine for the excision size.
• Complex repair (13100-13160): Separately billable when reconstruction requires advancement flaps, Z-plasty, or other complex techniques beyond layered closure. Documentation must describe the specific technique.

When billing an intermediate or complex repair alongside CPT Code 11644, append modifier 59 (or XS if on a distinct anatomical structure) to the repair code. Verify the current NCCI edit table before billing, as bundling rules are updated quarterly. The skin clinic software workflows that track procedure combinations help flag potential NCCI conflicts before claim submission.

CPT 11644 vs Mohs surgery: When to use each code

Mohs micrographic surgery is coded entirely separately from the 11640-11646 excision series. The two approaches serve different clinical purposes and have distinct coding, reimbursement, and documentation pathways.

Never use CPT Code 11644 for Mohs surgery. If the surgeon performs intraoperative margin analysis, the correct code series is 17311-17315 regardless of the anatomical site or lesion size.

Common billing errors for CPT Code 11644

Most denials and payment reductions on CPT Code 11644 trace back to a handful of recurring errors. Recognizing these patterns before submission is faster than appealing after a denial. The claims management software that dermatology practices use increasingly integrates pre-submission edits to catch these automatically.

• Measuring lesion only: Reporting only the lesion diameter without adding margins is the leading cause of downcoding. The stated diameter on the claim must equal the lesion plus all excised margins. A 2.4 cm lesion with 0.4 cm margins on each side has a 3.2 cm excised diameter, placing it in the CPT Code 11644 range, not in 11643.
• Using pathology dimensions: Pathology reports reflect post-fixation specimen size. Formalin shrinkage reduces dimensions by 10-20%. Always use the intraoperative measurement from the operative note, not the pathology report, for code selection.
• Bundling simple repair as a separate charge: Adding a simple repair code (12001-12021) alongside CPT Code 11644 triggers an automatic NCCI edit denial. Remove the repair code from the claim.
• Missing or inadequate pathology: Billing CPT Code 11644 before pathology results are available creates audit risk. If the lesion is later found to be benign, the malignant excision code is incorrect. Some practices hold the claim until pathology confirms.
• Site misidentification: CPT Code 11644 applies only to face, ears, eyelids, nose, and lips. Scalp, neck, hand, and trunk lesions of the same diameter use the 11601-11606 series. Using 11644 for a scalp lesion is a coding error, not a gray area.
• Modifier 50 on bilateral lesions: Two lesions excised from bilateral ears or eyelids require two separate line items with RT and LT modifiers, not a single line with modifier 50.

Coders can cross-reference ICD-10 codes to check site alignment using the AAPC crosswalk tool. Mismatches between the diagnosis code’s stated site and the CPT code’s anatomical site often appear here before they trigger a payer denial.

Conclusion

CPT Code 11644 is straightforward in concept but easy to misapply in practice. The excised diameter measurement, the NCCI bundling rule for simple repair, and the Mohs vs. excision distinction account for the majority of claim errors on this code.

Pabau’s claims management software helps dermatology and surgical practices build pre-submission edit checks for exactly these scenarios: Diameter measurement flags, NCCI bundling warnings, and ICD-10 site alignment checks. To see how Pabau supports dermatology billing workflows, book a demo with the team.

Continue your research

Billing intermediate wound repair? 12034 covers layered closure of deeper subcutaneous tissue when repair goes beyond simple closure.

Need a complex repair code? 13121 applies when reconstruction requires flaps or grafts beyond layered closure.

Coding surgical debridement? 11004 covers necrotizing soft tissue infection debridement, a related but distinct excision scenario.

Frequently Asked Questions