Is C4A a billable code?
No. C4A is a header code that groups 24 more specific codes. Use one of the billable codes listed on this page instead.
ICD-10-CM FY2027 diagnosis code
C4A: Merkel cell carcinoma
Header code: not billableValid for dates of service October 1, 2026 to September 30, 2027
C4A groups related diagnoses under merkel cell carcinoma. It cannot be used on a claim by itself. Choose the billable code below that matches the patient's record.
Billable codes under C4A
- C4A.0Merkel cell carcinoma of lip
- C4A.10Merkel cell carcinoma of unspecified eyelid, including canthus
- C4A.111Merkel cell carcinoma of right upper eyelid, including canthus
- C4A.112Merkel cell carcinoma of right lower eyelid, including canthus
- C4A.121Merkel cell carcinoma of left upper eyelid, including canthus
- C4A.122Merkel cell carcinoma of left lower eyelid, including canthus
- C4A.20Merkel cell carcinoma of unspecified ear and external auricular canal
- C4A.21Merkel cell carcinoma of right ear and external auricular canal
- C4A.22Merkel cell carcinoma of left ear and external auricular canal
- C4A.30Merkel cell carcinoma of unspecified part of face
- C4A.31Merkel cell carcinoma of nose
- C4A.39Merkel cell carcinoma of other parts of face
- C4A.4Merkel cell carcinoma of scalp and neck
- C4A.51Merkel cell carcinoma of anal skin
- C4A.52Merkel cell carcinoma of skin of breast
- C4A.59Merkel cell carcinoma of other part of trunk
- C4A.60Merkel cell carcinoma of unspecified upper limb, including shoulder
- C4A.61Merkel cell carcinoma of right upper limb, including shoulder
- C4A.62Merkel cell carcinoma of left upper limb, including shoulder
- C4A.70Merkel cell carcinoma of unspecified lower limb, including hip
- C4A.71Merkel cell carcinoma of right lower limb, including hip
- C4A.72Merkel cell carcinoma of left lower limb, including hip
- C4A.8Merkel cell carcinoma of overlapping sites
- C4A.9Merkel cell carcinoma, unspecified
C4A questions
What does C4A mean?
C4A is the ICD-10-CM code for Merkel cell carcinoma. It is in chapter 2, Neoplasms (C00-D49).
Code titles come from the official ICD-10-CM files published by the CDC National Center for Health Statistics. Always check payer rules and the clinical record before billing.