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v1.0.0
ICD-10 Guide
ICD-10 CodesChapter 2: NeoplasmsC21

C21

Billable

Malignant neoplasm of anus and anal canal

Chapter 2:Neoplasms

BILLABLE STATUSYes
IMPLEMENTATION DATEOctober 1, 2015
LAST UPDATED09/05/2025

Code Description

ICD-10 C21 is a billable code used to indicate a diagnosis of malignant neoplasm of anus and anal canal.

Key Diagnostic Point:

Malignant neoplasm of the anus and anal canal refers to cancerous growths that originate in the anal region, which includes the anus and the anal canal. This type of cancer is relatively rare compared to other colorectal cancers but has been increasing in incidence, particularly among certain populations. The primary risk factors include human papillomavirus (HPV) infection, immunosuppression, and a history of anal warts. Symptoms may include rectal bleeding, anal pain, and changes in bowel habits. Diagnosis typically involves a combination of physical examination, imaging studies, and biopsy. Staging of anal cancer is crucial for determining treatment options and prognosis, with the American Joint Committee on Cancer (AJCC) staging system commonly used. Treatment may involve surgery, radiation therapy, and chemotherapy, depending on the stage and location of the tumor. Microsatellite instability (MSI) testing may also be relevant in some cases, as it can influence treatment decisions, particularly in the context of immunotherapy. Early detection through screening is vital, especially for high-risk populations, to improve outcomes.

Code Complexity Analysis

Complexity Rating: Medium

Medium Complexity

Complexity Factors

  • Variability in staging and treatment protocols
  • Need for precise documentation of tumor location and size
  • Differentiation from benign anal conditions
  • Potential for multiple treatment modalities

Audit Risk Factors

  • Inadequate documentation of staging
  • Failure to specify the type of treatment received
  • Misclassification of tumor size or location
  • Lack of supporting documentation for co-morbid conditions

Specialty Focus

Medical Specialties

Oncology

Documentation Requirements

Detailed pathology reports, imaging studies, and treatment plans.

Common Clinical Scenarios

Diagnosis and management of anal cancer, including staging and treatment planning.

Billing Considerations

Ensure accurate documentation of tumor characteristics and treatment response.

Gastroenterology

Documentation Requirements

Endoscopy reports, biopsy results, and follow-up care documentation.

Common Clinical Scenarios

Screening for anal cancer in high-risk populations and management of anal dysplasia.

Billing Considerations

Document any findings from colonoscopy or other diagnostic procedures.

Coding Guidelines

Inclusion Criteria

Use C21 When
  • Follow the official ICD
  • CM coding guidelines, ensuring accurate documentation of the diagnosis, staging, and treatment
  • Include any relevant co
  • morbid conditions and specify the type of treatment received

Exclusion Criteria

Do NOT use C21 When
No specific exclusions found.

Related CPT Codes

45385CPT Code

Endoscopic biopsy of anal canal

Clinical Scenario

Used when a biopsy is performed to confirm anal cancer diagnosis.

Documentation Requirements

Document the indication for the biopsy and findings.

Specialty Considerations

Ensure that the procedure is linked to the diagnosis of anal cancer.

ICD-10 Impact

Diagnostic & Documentation Impact

Enhanced Specificity

ICD-10 Improvements

The transition to ICD-10 has allowed for more specific coding of anal cancers, improving the accuracy of data collection and reimbursement processes. This specificity aids in better tracking of treatment outcomes and epidemiological studies.

ICD-9 vs ICD-10

The transition to ICD-10 has allowed for more specific coding of anal cancers, improving the accuracy of data collection and reimbursement processes. This specificity aids in better tracking of treatment outcomes and epidemiological studies.

Reimbursement & Billing Impact

reimbursement processes. This specificity aids in better tracking of treatment outcomes and epidemiological studies.

Resources

Clinical References

  • •
    American Cancer Society - Anal Cancer

Coding & Billing References

  • •
    American Cancer Society - Anal Cancer

Frequently Asked Questions

What are the common symptoms of anal cancer?

Common symptoms include rectal bleeding, anal pain, a lump near the anus, and changes in bowel habits. If you experience any of these symptoms, it is important to consult a healthcare provider for evaluation.