1. ICD-10-CM Codes
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2. C00-D49
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3. C43-C4A
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4. C4A-
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5. 2023 ICD-10-CM Diagnosis Code C4A

2023 ICD-10-CM Diagnosis Code C4A

Merkel cell carcinoma

2016 2017 2018 2019 2020 2021 2022 2023 Non-Billable/Non-Specific Code

• C4A should not be used for reimbursement purposes as there are multiple codes below it that contain a greater level of detail.
• The 2023 edition of ICD-10-CM C4A became effective on October 1, 2022.
• This is the American ICD-10-CM version of C4A - other international versions of ICD-10 C4A may differ.

• A carcinoma arising from merkel cells located in the basal layer of the epidermis and occurring most commonly as a primary neuroendocrine carcinoma of the skin. Merkel cells are tactile cells of neuroectodermal origin and histologically show neurosecretory granules. The skin of the head and neck are a common site of merkel cell carcinoma, occurring generally in elderly patients. (holland et al., cancer medicine, 3d ed, p1245)
• A rare malignant cutaneous tumor seen in elderly patients. Its usual location is on the head, neck and extremities. The tumor is composed of small round cells with scanty cytoplasm arranged in a trabecular pattern, or in ill-defined nodules or in a diffuse pattern. The tumor cells contain cytoplasmic membrane-bound dense core granules resembling neurosecretory granules.
• A rare type of cancer that forms on or just beneath the skin, usually in parts of the body that have been exposed to the sun. It is most common in older people and in people with weakened immune systems.

• 2016 (effective 10/1/2015): New code (first year of non-draft ICD-10-CM)
• 2017 (effective 10/1/2016): No change
• 2018 (effective 10/1/2017): No change
• 2019 (effective 10/1/2018): No change
• 2020 (effective 10/1/2019): No change
• 2021 (effective 10/1/2020): No change
• 2022 (effective 10/1/2021): No change
• 2023 (effective 10/1/2022): No change

• Type 1 Excludes: C44
  ICD-10-CM Diagnosis Code C44

  Other and unspecified malignant neoplasm of skin

  2016 2017 2018 2019 2020 2021 2022 2023 Non-Billable/Non-Specific Code

  Includes

  • malignant neoplasm of sebaceous glands
  • malignant neoplasm of sweat glands

  Type 1 Excludes

  • Kaposi's sarcoma of skin (C46.0)
  • malignant melanoma of skin (C43.-)
  • malignant neoplasm of skin of genital organs (C51-C52, C60.-, C63.2)
  • Merkel cell carcinoma (C4A.-)
• Type 2 Excludes: C43
  , C7A
  ICD-10-CM Diagnosis Code C43

  Malignant melanoma of skin

  2016 2017 2018 2019 2020 2021 2022 2023 Non-Billable/Non-Specific Code

  Type 1 Excludes

  • melanoma in situ (D03.-)

  Type 2 Excludes

  • malignant melanoma of skin of genital organs (C51-C52, C60.-, C63.-)
  • Merkel cell carcinoma (C4A.-)
  • sites other than skin-code to malignant neoplasm of the site
  ICD-10-CM Diagnosis Code C7A

  Malignant neuroendocrine tumors

  2016 2017 2018 2019 2020 2021 2022 2023 Non-Billable/Non-Specific Code

  Code Also

  • any associated multiple endocrine neoplasia [MEN] syndromes (E31.2-)

  Type 2 Excludes

  • malignant pancreatic islet cell tumors (C25.4)
  • Merkel cell carcinoma (C4A.-)

  Use Additional

  • code to identify any associated endocrine syndrome, such as:
  • carcinoid syndrome (E34.0)
• Applicable To: Z85.821
  ICD-10-CM Diagnosis Code Z85.821

  Personal history of Merkel cell carcinoma

  2016 2017 2018 2019 2020 2021 2022 2023 Billable/Specific Code POA Exempt

  Applicable To

  • Conditions classifiable to C4A

Reimbursement claims with a date of service on or after October 1, 2015 require the use of ICD-10-CM codes.