2024 ICD-10-CM Diagnosis Code C21.0

Malignant neoplasm of anus, unspecified

  • C21.0 is a billable/specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes.
  • The 2024 edition of ICD-10-CM C21.0 became effective on October 1, 2023.
  • This is the American ICD-10-CM version of C21.0 – other international versions of ICD-10 C21.0 may differ.

The following code(s) above C21.0 contain annotation back-references

 that may be applicable to C21.0:

  • C00-D49  Neoplasms
  • C15-C26  Malignant neoplasms of digestive organs
  • C21  Malignant neoplasm of anus and anal canal

Approximate Synonyms

  • Cancer anal melanoma
  • Cancer of the anus
  • Cancer of the anus, adenocarcinoma
  • Cancer of the anus, squamous cell
  • Malignant melanoma of anus
  • Primary adenocarcinoma of anus
  • Primary malignant neoplasm of anus
  • Squamous cell carcinoma of anal margin

Clinical Information

  • A primary or metastatic malignant neoplasm that affects the anal canal or perianal skin. Representative examples include carcinomas, lymphomas, and melanomas.
  • Cancer relating to the anus. Tumors of the anal margin (below the anal verge and involving the perianal hair-bearing skin) are classified with skin tumors.

ICD-10-CM C21.0 is grouped within Diagnostic Related Group(s) (MS-DRG v41.0):

  • 374 Digestive malignancy with mcc
  • 375 Digestive malignancy with cc
  • 376 Digestive malignancy without cc/mcc

Convert C21.0 to ICD-9-CMCode History

  • 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
  • 2024 (effective 10/1/2023): No change

Code annotations containing back-references to C21.0:

Diagnosis Index entries containing back-references to C21.0: