ICD-10 C4A.122
Billable / Specific HCC v28: 12Merkel cell carcinoma of left lower eyelid, including canthus
About ICD-10-CM C4A.122
ICD-10-CM code C4A.122 represents Merkel cell carcinoma of left lower eyelid, including canthus. This is a billable/specific code in the Neoplasms chapter (block C4A). The 2026 edition of ICD-10-CM C4A.122 became effective on October 1, 2025.
Coding Tips for C4A.122
Specialist guidance from the PayerReady Medical Coding Team. Specificity warnings, HCC capture rules, sequencing notes.
C4A.122 is a CMS-HCC v28 risk-adjustment code (category 12). To count for the patient Risk Adjustment Factor (RAF), document the diagnosis with MEAT language each calendar year: Monitored, Evaluated, Assessed, Treated. A diagnosis on the problem list alone does not satisfy CMS RADV audit standards. Include the diagnosis in the assessment with current status and current treatment plan.
Medicare Advantage HCC Impact
Capture this diagnosis annually for accurate risk adjustment. Missed HCC captures are the #1 revenue leak in Medicare Advantage risk programs.
Medicare LCD Coverage for C4A.122
Local Coverage Determinations (LCDs) from CMS MACs that list C4A.122 as a covered diagnosis.
Showing top 10 of 771 total . Click a CPT for full coverage scope.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing C4A.122.
5 Medicare
CPT Codes Commonly Billed with C4A.122
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
- 67912 CMS LCD: Billing and Coding: Blepharoplasty, Eyelid Surgery, and Brow Lift CMS LCD
Codes Adjacent To C4A.122
Other codes in section C43-C44 (Melanoma and other malignant neoplasms of skin).
ICD-10 C4A.122, Billing FAQ
Is ICD-10 code C4A.122 billable? +
Yes, C4A.122 is a billable ICD-10-CM code that can appear as a primary or secondary diagnosis on claims.
Does C4A.122 affect Medicare Advantage HCC risk adjustment? +
Yes. C4A.122 maps to CMS-HCC v28 category 12. Capture this diagnosis annually for accurate Medicare Advantage risk score.
What CPT codes are commonly billed with C4A.122? +
Procedures frequently paired with C4A.122 include: 67912.
Get the full PayerReady toolkit
Free access to CPT/ICD-10 lookup, denial appeals, fee comparator, and claim auditing with credentialing enrollment.
Start free →Run this code through our claim audit tool
Check NCCI bundling, MUE limits, and modifier logic before submission.
Try the auditor →Did this page help?
Quick signal so we know what to improve.
If you want a code reference page that doesn't exist yet, email coding@payerready.com.
Tell us what's missing or wrong: coding@payerready.com. We respond within 5 business days.
Reviewed by the PayerReady Medical Coding Team
Verified against the CMS 2026 code set on May 31, 2026.
Powered by 11K CPT · 98K ICD-10 · 860K MPFS rates · 4.5M NCCI edits · 9.5M NPIs. Our data methodology · About our coding team