C4A.0 Merkel cell carcinoma of lip

Billable ICD-10-CM code, FY2026.

Excludes1 (never code together)

• malignant neoplasm of vermilion border of lip (C00.0-C00.2)

Risk adjustment (HCC)

• CMS-HCC V28: HCC 21 — Lymphoma and Other Cancers
• CMS-HCC V22: HCC 12 — Breast, Prostate, and Other Cancers and Tumors
• RxHCC V08: HCC 22 — Prostate, Breast, Bladder, and Other Cancers and Tumors
• ESRD V24: HCC 12

MS-DRG index

Defines the logic of DRG(s) 595-596 in MDC 09.

Approximate ICD-9-CM (GEMs)

• 209.31 Merkel cell carcinoma of the face (approximate)

Code annotations containing back-references to C4A.0

Back-references to C4A.0

• Type 1 Excludes: C00 Malignant neoplasm of lip ("Merkel cell carcinoma of lip (C4A.0)")

Back-references to C4A

• Type 2 Excludes: C43 Malignant melanoma of skin ("Merkel cell carcinoma (C4A.-)")
• Type 1 Excludes: C44 Other and unspecified malignant neoplasm of skin ("Merkel cell carcinoma (C4A.-)")
• Type 2 Excludes: C7A Malignant neuroendocrine tumors ("Merkel cell carcinoma (C4A.-)")

Diagnosis Index entries for C4A.0

• Carcinoma (malignant) › Merkel cell › lip

Nearby codes

• C4A Merkel cell carcinoma
• C4A.0 Merkel cell carcinoma of lip (this code)
• C4A.1 Merkel cell carcinoma of eyelid, including canthus
• C4A.10 Merkel cell carcinoma of unspecified eyelid, including canthus
• C4A.11 Merkel cell carcinoma of right eyelid, including canthus
• C4A.111 Merkel cell carcinoma of right upper eyelid, including canthus
• C4A.112 Merkel cell carcinoma of right lower eyelid, including canthus