ICD-10 Diagnosis Code C21

Malignant neoplasm of anus and anal canal

Diagnosis Code C21

ICD-10: C21
Short Description: Malignant neoplasm of anus and anal canal
Long Description: Malignant neoplasm of anus and anal canal
This is the 2017 version of the ICD-10-CM diagnosis code C21

Not Valid for Submission
The code C21 is a "header" and not valid for submission for HIPAA-covered transactions.

Code Classification
  • Neoplasms (C00–D48)
    • Malignant neoplasms of digestive organs (C15-C26)
      • Malignant neoplasm of anus and anal canal (C21)

Information for Medical Professionals

Index of Diseases and Injuries
References found for the code C21 in the Index of Diseases and Injuries:

    • Type 2 Excludes Notes: Additional informationCallout Tooltip"And"
      The word “and” should be interpreted to mean either “and” or “or” when it appears in a title.
      • malignant carcinoid tumors of the colon (C7A.02-)
      • malignant melanoma of anal margin (C43.51)
      • malignant melanoma of anal skin (C43.51)
      • malignant melanoma of perianal skin (C43.51)
      • other and unspecified malignant neoplasm of anal margin (C44.500, C44.510, C44.520, C44.590)
      • other and unspecified malignant neoplasm of anal skin (C44.500, C44.510, C44.520, C44.590)
      • other and unspecified malignant neoplasm of perianal skin (C44.500, C44.510, C44.520, C44.590)

Information for Patients


Anal Cancer

The anus is where stool leaves your body when you go to the bathroom. It is made up of your outer layers of skin and the end of your large intestine. Anal cancer is a disease in which cancer cells form in the tissues of the anus.

Anal cancer is rare. It is more common in smokers and people over 50. You are also at higher risk if you have HPV, have anal sex, or have many sexual partners.

Symptoms include bleeding, pain, or lumps in the anal area. Anal itching and discharge can also be signs of anal cancer.

Doctors use tests that examine the anus to diagnose anal cancer. They include a physical exam, endoscopy, ultrasound, and biopsy.

Treatments include radiation therapy, chemotherapy, and surgery.

NIH: National Cancer Institute

  • After chemotherapy - discharge
  • Anal cancer
  • Anoscopy
  • Pelvic (between the hips) radiation - discharge
  • Understanding Chemotherapy - NIH - Easy-to-Read (National Cancer Institute)
  • What to Know about External Beam Radiation Therapy - NIH - Easy-to-Read (National Cancer Institute)


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