ICD-10-CM diagnosis code
C4A.10 Merkel cell carcinoma of unspecified eyelid, including canthus
- Billable
- Yes, a complete code (FY2026)
- Category
- C4A
- Chapter
- 2. Neoplasms
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Other codes in C4A
24 complete codes in this category.
- 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
Documentation tips
- Make sure the note supports every element of the title, “Merkel cell carcinoma of unspecified eyelid, including canthus”: each detail in it should be traceable to the history, examination or assessment.
- Code to the highest specificity the documentation supports. If a detail is missing from the note, add it to the note rather than choosing a less specific code by default.
- Check the Tabular List and official guidelines for instructional notes (“code first”, “use additional code”, Excludes1/Excludes2) that apply to C4A.
ICD-10-CM is developed by the National Center for Health Statistics (NCHS), Centers for Disease Control and Prevention, U.S. Department of Health and Human Services, and is based on the WHO ICD-10. Codes and titles are reproduced unchanged from the FY2026 code list (effective 1 October 2025). Their use here does not imply endorsement by CDC, HHS or the U.S. Government. Changes effective on or after 1 October 2026 may not be reflected yet; check the current release at cdc.gov or cms.gov before submitting claims.
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