2021 ICD-10-CM Code C4A.20

Merkel cell carcinoma of unspecified ear and external auricular canal

Version 2021
Billable Code
Unspecified Code
MS-DRG Mapping

Valid for Submission

C4A.20 is a billable diagnosis code used to specify a medical diagnosis of merkel cell carcinoma of unspecified ear and external auricular canal. The code C4A.20 is valid during the fiscal year 2021 from October 01, 2020 through September 30, 2021 for the submission of HIPAA-covered transactions.

Unspecified diagnosis codes like C4A.20 are acceptable when clinical information is unknown or not available about a particular condition. Although a more specific code is preferable, unspecified codes should be used when such codes most accurately reflect what is known about a patient's condition. Specific diagnosis codes should not be used if not supported by the patient's medical record.

ICD-10:C4A.20
Short Description:Merkel cell carcinoma of unsp ear and external auric canal
Long Description:Merkel cell carcinoma of unspecified ear and external auricular canal

Code Classification

Convert C4A.20 to ICD-9 Code

The General Equivalency Mapping (GEM) crosswalk indicates an approximate mapping between the ICD-10 code C4A.20 its ICD-9 equivalent. The approximate mapping means there is not an exact match between the ICD-10 code and the ICD-9 code and the mapped code is not a precise representation of the original code.

Information for Patients


Skin Cancer

Skin cancer is the most common form of cancer in the United States. The two most common types are basal cell cancer and squamous cell cancer. They usually form on the head, face, neck, hands, and arms. Another type of skin cancer, melanoma, is more dangerous but less common.

Anyone can get skin cancer, but it is more common in people who

You should have your doctor check any suspicious skin markings and any changes in the way your skin looks. Treatment is more likely to work well when cancer is found early. If not treated, some types of skin cancer cells can spread to other tissues and organs. Treatments include surgery, radiation therapy, chemotherapy, photodynamic therapy (PDT), and biologic therapy. PDT uses a drug and a type of laser light to kill cancer cells. Biologic therapy boosts your body's own ability to fight cancer.

NIH: National Cancer Institute


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Code History

  • FY 2021 - No Change, effective from 10/1/2020 through 9/30/2021
  • FY 2020 - No Change, effective from 10/1/2019 through 9/30/2020
  • FY 2019 - No Change, effective from 10/1/2018 through 9/30/2019
  • FY 2018 - No Change, effective from 10/1/2017 through 9/30/2018
  • FY 2017 - No Change, effective from 10/1/2016 through 9/30/2017
  • FY 2016 - New Code, effective from 10/1/2015 through 9/30/2016 (First year ICD-10-CM implemented into the HIPAA code set)