ICDcodes.org
FY2027

C4A.9 — Merkel cell carcinoma, unspecified

BillableUnspecified

Is C4A.9 billable?

Yes, but C4A.9 is an unspecified code. C4A.9 is a valid, billable ICD-10-CM code for encounters from October 1, 2026 through September 30, 2027. However, C4A.9 is an unspecified or catch-all code. Payers apply additional scrutiny to unspecified codes and many deny them when the medical record supports a more specific option, so check the documentation before selecting C4A.9 — the more specific alternatives are listed below.

C4A.9 at a glance

CodeC4A.9
DescriptionMerkel cell carcinoma, unspecified
BillableYes
Code setICD-10-CM FY2027
Valid for encountersOctober 1, 2026 – September 30, 2027

Which MS-DRGs does C4A.9 group to?

C4A.9 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.9 listed in the Alphabetic Index?

These are the routes through the Alphabetic Index that lead to C4A.9. They show the wording a clinician may have documented, which often differs from the Tabular description.

  • Carcinoma › Merkel cell (malignant)

Inclusion terms

Alternative wording in documentation that is classified to C4A.9.

  • Merkel cell carcinoma of unspecified site
  • Merkel cell carcinoma NOS

How long has C4A.9 existed?

C4A.9 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.

What other codes are in the C4A family? (9)