Merkel cell carcinoma

Official coding guidelines

From the ICD-10-CM Official Guidelines for Coding and Reporting, FY 2027 (CMS and NCHS). Links open the PDF at the right page.

Rules for coding benign and malignant neoplasms: using the Neoplasm Table, sequencing primary and secondary sites, treatment encounters, complications, and current cancer versus personal history.

• Admission/Encounter for treatment of primary site (page 33)
• Admission/Encounter for treatment of secondary site (page 33)
• Coding and sequencing of complications (page 34)
• Primary malignancy previously excised (page 34)
• Admissions/Encounters involving antineoplastic chemotherapy, immunotherapy and radiation therapy (page 35)
• Admission/encounter to determine extent of malignancy (page 36)
• Symptoms, signs, and abnormal findings listed in Chapter 18 associated with neoplasms (page 36)
• Admission/encounter for pain control/management (page 36)

Read Section I.C.2 (page 32), 12 more topics

All codes under C4A

C4A can't be used on a claim. Pick a billable code below; grey headings group them.

• C4A.0Merkel cell carcinoma of lip
• C4A.1Merkel cell carcinoma of eyelid, including canthus
• C4A.10Merkel cell carcinoma of unspecified eyelid, including canthus
• C4A.11Merkel cell carcinoma of right eyelid, including canthus
• C4A.111Merkel cell carcinoma of right upper eyelid, including canthus
• C4A.112Merkel cell carcinoma of right lower eyelid, including canthus
• C4A.12Merkel cell carcinoma of left eyelid, including canthus
• C4A.121Merkel cell carcinoma of left upper eyelid, including canthus
• C4A.122Merkel cell carcinoma of left lower eyelid, including canthus
• C4A.2Merkel cell carcinoma of ear and external auricular canal
• C4A.20Merkel cell carcinoma of unspecified ear and external auricular canal
• C4A.21Merkel cell carcinoma of right ear and external auricular canal
• C4A.22Merkel cell carcinoma of left ear and external auricular canal
• C4A.3Merkel cell carcinoma of other and unspecified parts of face
• C4A.30Merkel cell carcinoma of unspecified part of face
• C4A.31Merkel cell carcinoma of nose
• C4A.39Merkel cell carcinoma of other parts of face
• C4A.4Merkel cell carcinoma of scalp and neck
• C4A.5Merkel cell carcinoma of trunk
• C4A.51Merkel cell carcinoma of anal skin
• C4A.52Merkel cell carcinoma of skin of breast
• C4A.59Merkel cell carcinoma of other part of trunk
• C4A.6Merkel cell carcinoma of upper limb, including shoulder
• C4A.60Merkel cell carcinoma of unspecified upper limb, including shoulder
• C4A.61Merkel cell carcinoma of right upper limb, including shoulder
• C4A.62Merkel cell carcinoma of left upper limb, including shoulder
• C4A.7Merkel cell carcinoma of lower limb, including hip
• C4A.70Merkel cell carcinoma of unspecified lower limb, including hip
• C4A.71Merkel cell carcinoma of right lower limb, including hip
• C4A.72Merkel cell carcinoma of left lower limb, including hip
• C4A.8Merkel cell carcinoma of overlapping sites
• C4A.9Merkel cell carcinoma, unspecified

C4A MS-DRGs

As the principal diagnosis, all 24 billable codes under C4A group to MS-DRG 595 or 596 (v44.0). Which one applies depends on procedures performed, secondary diagnoses (CC/MCC), and the patient's age and discharge status.

• DRG 595 Major Skin Disorders with MCC
• DRG 596 Major Skin Disorders without MCC

Other codes that refer to C4A

Notes on these codes point to C4A.

• C43 Excludes2: Merkel cell carcinoma (C4A.-)
• C44 Excludes1: Merkel cell carcinoma (C4A.-)
• C7A Excludes2: Merkel cell carcinoma (C4A.-)
• Z85.821 Includes: Conditions classifiable to C4A

About the condition

Plain-language background from MedlinePlus (National Library of Medicine), not coding guidance.

Code history

Valid since FY2016, when ICD-10-CM took effect on October 1, 2015. No changes since.