ICD-10 Diagnosis Code C4A.121

Merkel cell carcinoma of left upper eyelid, inc canthus

Diagnosis Code C4A.121

ICD-10: C4A.121
Short Description: Merkel cell carcinoma of left upper eyelid, inc canthus
Long Description: Merkel cell carcinoma of left upper eyelid, including canthus
This is the 2019 version of the ICD-10-CM diagnosis code C4A.121

Valid for Submission
The code C4A.121 is valid for submission for HIPAA-covered transactions.

New 2019 ICD-10 Code
C4A.121 is new to ICD-10 code set for the FY 2019, effective October 1, 2018. The National Center for Health Statistics (NCHS) has published an update to the ICD-10-CM diagnosis codes which became effective October 1, 2018. This is a new and revised code for the FY 2019 (October 1, 2018 - September 30, 2019).

Code Classification
  • Neoplasms (C00–D48)
    • Melanoma and other malignant neoplasms of skin (C43-C44)
      • Merkel cell carcinoma (C4A)
Version 2019 Billable Code New Code

Information for Medical Professionals

Diagnostic Related Groups
The diagnosis code C4A.121 is grouped in the following Diagnostic Related Group(s) (MS-DRG V35.0)

  • 595 - MAJOR SKIN DISORDERS WITH MCC
  • 596 - MAJOR SKIN DISORDERS WITHOUT MCC

Replacement Code
This code replaces the following previously assigned ICD-10 code(s) listed below:
  • C4A.12 - Merkel cell carcinoma of left eyelid, including canthus


ICD-10 Footnotes

General Equivalence Map Definitions
The ICD-10 and ICD-9 GEMs are used to facilitate linking between the diagnosis codes in ICD-9-CM and the new ICD-10-CM code set. The GEMs are the raw material from which providers, health information vendors and payers can derive specific applied mappings to meet their needs.

  • Approximate Flag - The approximate flag is on, indicating that the relationship between the code in the source system and the code in the target system is an approximate equivalent.
  • No Map Flag - The no map flag indicates that a code in the source system is not linked to any code in the target system.
  • Combination Flag - The combination flag indicates that more than one code in the target system is required to satisfy the full equivalent meaning of a code in the source system.

Present on Admission
The Present on Admission (POA) indicator is used for diagnosis codes included in claims involving inpatient admissions to general acute care hospitals. POA indicators must be reported to CMS on each claim to facilitate the grouping of diagnoses codes into the proper Diagnostic Related Groups (DRG). CMS publishes a listing of specific diagnosis codes that are exempt from the POA reporting requirement.

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