The following codes as of October 2024 are provided as a reference and may be relevant when billing for KEYTRUDA and
its administration. Consult the relevant manual and/or other guidelines for a description of each code to determine
the appropriateness of its use and for information on additional codes. Diagnosis codes should be selected only by a
health care professional. You are solely responsible for determining the appropriate codes and for any action you
take in billing.
When submitting a claim for KEYTRUDA, always verify coding requirements with the relevant payer. Coding
requirements may vary by insurer or plan; please refer to the payer-specific policies to understand what may be
covered.
Check with the relevant payer regarding guidance on which diagnoses they will recognize and the applicability of
secondary codes. Health care professionals are solely responsible for selecting codes that appropriately reflect the
patient’s diagnosis, the services rendered, and the applicable payers’ guidelines.
Providers should document the diagnosis with a sufficiently high degree of specificity based on the information
available to enable the identification of the most appropriate code. Although CMS has said that an unspecified code
may be appropriate in some cases, CMS has advised that you should always code with as much specificity as possible
consistent with the clinical documentation.
Merck and its agents make no warranties concerning the accuracy or appropriateness of this information for your
particular use given the frequent changes in public and private payer billing. Merck cautions that payer-coding
requirements vary and can frequently change, so it is important to regularly check with each payer or, where
applicable, the Medicare Administrative Contractor as to payer-specific requirements. The use of this information
does not guarantee payment or that any payment received will cover your costs.
Indication
KEYTRUDA is indicated for the treatment of adult and pediatric patients with recurrent locally advanced or
metastatic Merkel cell carcinoma (MCC).
FDA-Approved Dosing
The FDA-approved dose of KEYTRUDA in adults is either 200 mg administered after dilution as an intravenous infusion
over 30 minutes every 3 weeks or 400 mg administered after dilution as an intravenous infusion over 30 minutes every
6 weeks, until disease progression, unacceptable toxicity, or up to 24 months.
The FDA-approved dose of KEYTRUDA in pediatric patients is 2 mg/kg (up to a maximum of 200 mg), administered after
dilution as an intravenous infusion over 30 minutes every 3 weeks until disease progression, unacceptable toxicity,
or up to 24 months.
See full Prescribing Information for preparation and administration instructions and dosage modifications for
adverse reactions.
Possible relevant diagnosis codes for advanced Merkel cell carcinoma
Learn more about each diagnosis code and descriptor by selecting from the series options below.
C4A.0: Merkel Cell Carcinoma of Lip4
ICD-10-CM CODE
DESCRIPTOR
C4A.0
Merkel cell carcinoma of lip
Excludes: malignant neoplasm of vermilion border of lip (C00.0-C00.2)
C4A.1: Merkel Cell Carcinoma of Eyelid, Including Canthus4
ICD-10-CM CODE
DESCRIPTOR
C4A.10
Merkel cell carcinoma of unspecified eyelid, including canthus
C4A.11: Merkel Cell Carcinoma of Right Eyelid, Including Canthus4
ICD-10-CM CODE
DESCRIPTOR
C4A.111
Merkel cell carcinoma of right upper eyelid, including canthus
C4A.112
Merkel cell carcinoma of right lower eyelid, including canthus
C4A.12: Merkel Cell Carcinoma of Left Eyelid, Including Canthus4
ICD-10-CM CODE
DESCRIPTOR
C4A.121
Merkel cell carcinoma of left upper eyelid, including canthus
C4A.122
Merkel cell carcinoma of left lower eyelid, including canthus
C4A.2: Merkel Cell Carcinoma of Ear and External Auricular Canal4
ICD-10-CM CODE
DESCRIPTOR
C4A.20
Merkel cell carcinoma of unspecified ear and external auricular canal
C4A.21
Merkel cell carcinoma of right ear and external auricular canal
C4A.22
Merkel cell carcinoma of left ear and external auricular canal
C4A.3: Merkel Cell Carcinoma of Other and Unspecified Parts of Face4
ICD-10-CM CODE
DESCRIPTOR
C4A.30
Merkel cell carcinoma of unspecified part of face
C4A.31
Merkel cell carcinoma of nose
C4A.39
Merkel cell carcinoma of other parts of face
C4A.4: Merkel Cell Carcinoma of Scalp and Neck4
ICD-10-CM CODE
DESCRIPTOR
C4A.4
Merkel cell carcinoma of scalp and neck
C4A.5: Merkel Cell Carcinoma of Trunk4
The C4A.5 series excludes malignant neoplasm of anus not otherwise specified and malignant neoplasm of
scrotum
ICD-10-CM CODE
DESCRIPTOR
C4A.51
Merkel cell carcinoma of anal skin
Merkel cell carcinoma of anal margin
Merkel cell carcinoma of perianal skin
C4A.52
Merkel cell carcinoma of skin of breast
C4A.59
Merkel cell carcinoma of other part of trunk
C4A.6: Merkel Cell Carcinoma of Upper Limb, Including Shoulder4
ICD-10-CM CODE
DESCRIPTOR
C4A.60
Merkel cell carcinoma of unspecified upper limb, including shoulder
C4A.61
Merkel cell carcinoma of right upper limb, including shoulder
C4A.62
Merkel cell carcinoma of left upper limb, including shoulder
C4A.7: Merkel Cell Carcinoma of Lower Limb, Including Hip4
ICD-10-CM CODE
DESCRIPTOR
C4A.70
Merkel cell carcinoma of unspecified lower limb, including hip
C4A.71
Merkel cell carcinoma of right lower limb, including hip
C4A.72
Merkel cell carcinoma of left lower limb, including hip
C4A.8: Merkel Cell Carcinoma of Overlapping Sites4