C4AHeader code — not billable
Merkel cell carcinoma
- Chapter
- 2. Neoplasms
- Category
- C4A
- Effective date
- October 1, 2026
Related codes in category C4A
C4A.0Merkel cell carcinoma of lipYesC4A.1Merkel cell carcinoma of eyelid, including canthusC4A.10Merkel cell carcinoma of unsp eyelid, including canthusYesC4A.11Merkel cell carcinoma of right eyelid, including canthusC4A.111Merkel cell carcinoma of right upper eyelid, inc canthusYesC4A.112Merkel cell carcinoma of right lower eyelid, inc canthusYesC4A.12Merkel cell carcinoma of left eyelid, including canthusC4A.121Merkel cell carcinoma of left upper eyelid, inc canthusYesC4A.122Merkel cell carcinoma of left lower eyelid, inc canthusYesC4A.2Merkel cell carcinoma of ear and external auricular canalC4A.20Merkel cell carcinoma of unsp ear and external auric canalYesC4A.21Merkel cell carcinoma of right ear and external auric canalYes
Frequently asked questions
What is ICD-10 code C4A?
C4A is an ICD-10-CM diagnosis code for Merkel cell carcinoma.
Is C4A a billable code?
No. C4A is a category/header code, not billable on its own — use one of its more specific child codes instead.
What ICD-10-CM chapter is C4A in?
C4A falls under Chapter 2: Neoplasms.
When did C4A become effective?
C4A has been effective since October 1, 2026, per the CMS/CDC ICD-10-CM annual release.
What other codes are related to C4A?
C4A belongs to category C4A, which includes 12 other codes — see the related codes list on this page.
ICD-10-CM data maintained by CDC/CMS (public domain). Always verify codes with authoritative sources before making coding or billing decisions.