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v1.0.0
ICD-10 Guide
ICD-10 CodesC80.1

C80.1

Billable

Malignant (primary) neoplasm, unspecified

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

Code Description

ICD-10 C80.1 is a billable code used to indicate a diagnosis of malignant (primary) neoplasm, unspecified.

Key Diagnostic Point:

C80.1 refers to a malignant neoplasm where the primary site is not specified. This code is often used in cases where the cancer has metastasized, and the origin of the primary tumor is unknown. Patients may present with symptoms related to metastatic disease, such as unexplained weight loss, pain, or organ dysfunction, but without a clear identification of the primary tumor. This situation can arise in various clinical scenarios, including advanced cancer cases where diagnostic imaging and biopsies have not revealed the primary site. Staging of the disease is crucial, as it influences treatment decisions and prognosis. In palliative care, the focus shifts to managing symptoms and improving quality of life, as the primary tumor may not be treatable. Accurate coding is essential for appropriate reimbursement and to reflect the complexity of the patient's condition.

Code Complexity Analysis

Complexity Rating: High

High Complexity

Complexity Factors

  • Difficulty in determining the primary site of cancer
  • Need for comprehensive documentation of metastatic disease
  • Variability in clinical presentation and symptoms
  • Potential for multiple diagnostic tests and imaging studies

Audit Risk Factors

  • Inadequate documentation of the metastatic site
  • Failure to specify the unknown primary site
  • Inconsistent staging information
  • Lack of clarity in treatment plans

Specialty Focus

Medical Specialties

Oncology

Documentation Requirements

Detailed history of cancer diagnosis, treatment history, and results of imaging studies.

Common Clinical Scenarios

Patients presenting with symptoms of metastatic disease without a known primary tumor.

Billing Considerations

Ensure thorough documentation of all diagnostic efforts to identify the primary site.

Palliative Care

Documentation Requirements

Focus on symptom management, quality of life assessments, and treatment goals.

Common Clinical Scenarios

Patients with advanced cancer requiring symptom control and supportive care.

Billing Considerations

Documenting the patient's functional status and response to palliative interventions.

Coding Guidelines

Inclusion Criteria

Use C80.1 When
  • Follow official coding guidelines for neoplasms, ensuring that the documentation supports the use of C80
  • This includes confirming that the primary site is indeed unknown and that all efforts to identify it have been documented

Exclusion Criteria

Do NOT use C80.1 When
No specific exclusions found.

Related ICD-10 Codes

Related CPT Codes

99223CPT Code

Initial hospital care, typically 70 minutes or more

Clinical Scenario

Used for inpatient visits for patients with complex cancer cases.

Documentation Requirements

Document the patient's history, examination findings, and medical decision-making.

Specialty Considerations

Oncology specialists should ensure comprehensive documentation of cancer staging and treatment plans.

ICD-10 Impact

Diagnostic & Documentation Impact

Enhanced Specificity

ICD-10 Improvements

The transition to ICD-10 has allowed for more specific coding of cancer diagnoses, including the ability to capture cases where the primary site is unknown. This has implications for treatment planning and reimbursement.

ICD-9 vs ICD-10

The transition to ICD-10 has allowed for more specific coding of cancer diagnoses, including the ability to capture cases where the primary site is unknown. This has implications for treatment planning and reimbursement.

Reimbursement & Billing Impact

reimbursement.

Resources

Clinical References

  • •
    ICD-10-CM Official Guidelines for Coding and Reporting

Coding & Billing References

  • •
    ICD-10-CM Official Guidelines for Coding and Reporting

Frequently Asked Questions

When should I use C80.1?

C80.1 should be used when a malignant neoplasm is present, but the primary site cannot be determined despite thorough diagnostic efforts.