ICD-10-CM 2027 diagnosis code
C4A.12Merkel cell carcinoma of left eyelid, including canthus
C4A.12 is a header code, so it can't be reported by itself. Choose one of the 2 more specific codes beneath it.
Code last changed in FY2019 (effective October 1, 2018). Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data
About C4A.12
C4A.12 is the ICD-10-CM diagnosis code for Merkel cell carcinoma of left eyelid, including canthus. It belongs to category C4A (Merkel cell carcinoma), block C43-C44 (melanoma and other malignant neoplasms of skin) and chapter 2 (neoplasms). It is a header code, so it can't be reported by itself; one of its 2 subcodes must be used instead.
Within C4A.1 (Merkel cell carcinoma of eyelid, including canthus), C4A.12 is specifically for Merkel cell carcinoma of left eyelid, including canthus. Related codes cover unspecified eyelid, including canthus (C4A.10) and right eyelid, including canthus (C4A.11).
To report this condition, pick the subcode that matches the documentation: C4A.121 (canthus) and C4A.122 (canthus).
It has been part of ICD-10-CM since the code set took effect on October 1, 2015, and changed in FY2019 (expanded into subcodes).
Before ICD-10, this condition was coded in ICD-9-CM as 209.31 (Merkel cell carcinoma of the face).
Specific codes under C4A.12
Notes that apply from higher levels
Instructions written at a parent level also apply to C4A.12.
Broader instructions also apply from Chapter 2: Neoplasms.
ICD-9-CM equivalent
Converter →- 209.31Merkel cell carcinoma of the faceapproximate
From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.
Code history
- 2016
- 2017
- 2018
- 2019
- 2020
- 2021
- 2022
- 2023
- 2024
- 2025
- 2026
- 2027
- FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
- FY2019 (effective 10/1/2018): Expanded — no longer billable