C4A.21 — Merkel cell carcinoma of right ear and external auricular canal
Is C4A.21 billable?
Yes — C4A.21 is billable for FY2027. C4A.21 is a valid, billable ICD-10-CM code at the highest level of specificity in its branch. C4A.21 may be submitted for encounters from October 1, 2026 through September 30, 2027.
C4A.21 at a glance
| Code | C4A.21 |
|---|---|
| Description | Merkel cell carcinoma of right ear and external auricular canal |
| Billable | Yes |
| Code set | ICD-10-CM FY2027 |
| Valid for encounters | October 1, 2026 – September 30, 2027 |
Which MS-DRGs does C4A.21 group to?
C4A.21 sits in MDC 09 and helps define the logic of 2 MS-DRGs (version 44, FY2027). Which one a stay actually groups to also depends on procedures and secondary diagnoses.
- 595Major Skin Disorders with MCCmedical
- 596Major Skin Disorders without MCCmedical
How is C4A.21 listed in the Alphabetic Index?
The Alphabetic Index lists these routes under C4A.2, the nearest indexed parent of C4A.21. Use them to find the family, then select the specific code.
- Carcinoma › Merkel cell › ear and external auricular canal (malignant)
- Carcinoma › Merkel cell › external auricular canal (malignant)
How long has C4A.21 existed?
C4A.21 has been in ICD-10-CM since at least FY2016, the earliest fiscal year on record here.
Derived from the official order files for FY2016–FY2026. FY2017 and FY2020 publish no order file, so those years are not covered.