C4A.51 — Merkel cell carcinoma of anal skin
Is C4A.51 billable?
Yes — C4A.51 is billable for FY2027. C4A.51 is a valid, billable ICD-10-CM code at the highest level of specificity in its branch. C4A.51 may be submitted for encounters from October 1, 2026 through September 30, 2027.
C4A.51 at a glance
| Code | C4A.51 |
|---|---|
| Description | Merkel cell carcinoma of anal skin |
| Billable | Yes |
| Code set | ICD-10-CM FY2027 |
| Valid for encounters | October 1, 2026 – September 30, 2027 |
Which MS-DRGs does C4A.51 group to?
C4A.51 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.51 listed in the Alphabetic Index?
These are the routes through the Alphabetic Index that lead to C4A.51. They show the wording a clinician may have documented, which often differs from the Tabular description.
- Carcinoma › Merkel cell › anal margin (malignant)
- Carcinoma › Merkel cell › anal skin (malignant)
- Carcinoma › Merkel cell › perianal skin (malignant)
Inclusion terms
Alternative wording in documentation that is classified to C4A.51.
- Merkel cell carcinoma of anal margin
- Merkel cell carcinoma of perianal skin
Excludes2 — not included here — inherited from C4A.5
The conditions below are not part of C4A.51, but a patient may have both at the same time. When documentation supports it, C4A.51 and the excluded code may both be reported.
How long has C4A.51 existed?
C4A.51 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.