C4A – Merkel cell carcinoma
ICD-10-CM 2027 diagnosis code · Melanoma and other malignant neoplasms of skin
ICD-10-CM code
C4A
- Code
C4A(claims format:C4A)- Description
- Merkel cell carcinoma
- Billable
- No – use a more specific code below
- Valid for
- Dates of service October 1, 2026 – September 30, 2027 (FY2027)
- Chapter
- 2. Neoplasms (C00-D49)
- Block
- C43-C44 Melanoma and other malignant neoplasms of skin
Billable codes under C4A
C4A is a header code and cannot be used on claims. Choose the most specific code:
- C4A.0 – Merkel cell carcinoma of lipBillable
- C4A.1 – Merkel cell carcinoma of eyelid, including canthusHeader (more codes below)
- C4A.2 – Merkel cell carcinoma of ear and external auricular canalHeader (more codes below)
- C4A.3 – Merkel cell carcinoma of other and unspecified parts of faceHeader (more codes below)
- C4A.4 – Merkel cell carcinoma of scalp and neckBillable
- C4A.5 – Merkel cell carcinoma of trunkHeader (more codes below)
- C4A.6 – Merkel cell carcinoma of upper limb, including shoulderHeader (more codes below)
- C4A.7 – Merkel cell carcinoma of lower limb, including hipHeader (more codes below)
- C4A.8 – Merkel cell carcinoma of overlapping sitesBillable
- C4A.9 – Merkel cell carcinoma, unspecifiedBillable
Frequently asked questions
What is ICD-10 code C4A?
C4A is the ICD-10-CM code for merkel cell carcinoma, in the block C43-C44 (Melanoma and other malignant neoplasms of skin).
Is C4A a billable code?
No. C4A is a header code with more specific child codes; report one of the billable codes listed above.
Source: CDC/NCHS ICD-10-CM FY2027 code files, tabular list and index. Reference only – code assignment must follow the official ICD-10-CM guidelines and documentation in the medical record.