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ICD-10 Guide
ICD-10 CodesB46.3

B46.3

Tinea unguium

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

Code Description

ICD-10 B46.3 is a billable code used to indicate a diagnosis of tinea unguium.

Key Diagnostic Point:

Tinea unguium, also known as onychomycosis, is a fungal infection that affects the nails, particularly the toenails. It is characterized by the thickening, discoloration, and possible separation of the nail from the nail bed. The infection is primarily caused by dermatophytes, but non-dermatophyte molds and yeasts can also be responsible. Tinea unguium is more prevalent in individuals with compromised immune systems, diabetes, or peripheral vascular disease. Symptoms may include nail brittleness, crumbling, and a foul odor. Diagnosis is typically made through clinical examination and confirmed by laboratory tests, such as nail clippings sent for fungal culture or KOH preparation. Treatment options include topical antifungals like ciclopirox and systemic antifungals such as terbinafine and itraconazole. The choice of treatment may depend on the severity of the infection, the patient's overall health, and the presence of any underlying conditions. In immunocompromised patients, the risk of severe infection increases, necessitating more aggressive treatment and monitoring.

Code Complexity Analysis

Complexity Rating: Medium

Medium Complexity

Complexity Factors

  • Differentiating between types of fungal infections
  • Identifying immunocompromised patients
  • Understanding treatment options and their implications
  • Documenting clinical findings accurately

Audit Risk Factors

  • Inadequate documentation of the diagnosis
  • Failure to specify the type of fungus
  • Lack of evidence for immunocompromised status
  • Incorrect coding of associated conditions

Specialty Focus

Medical Specialties

Dermatology

Documentation Requirements

Detailed clinical notes on nail examination, treatment plans, and follow-up.

Common Clinical Scenarios

Patients presenting with nail discoloration, thickening, or pain.

Billing Considerations

Ensure accurate documentation of the type of fungus and any underlying conditions.

Infectious Disease

Documentation Requirements

Comprehensive history of immunocompromised status and treatment response.

Common Clinical Scenarios

Patients with recurrent fungal infections or those with systemic symptoms.

Billing Considerations

Document any systemic treatments and their effects on the fungal infection.

Coding Guidelines

Inclusion Criteria

Use B46.3 When
  • Follow the official ICD
  • CM coding guidelines for fungal infections, ensuring to document the specific type of fungus and any relevant patient history
  • existing

Exclusion Criteria

Do NOT use B46.3 When
  • Exclude codes for other nail conditions unless they are co

Related CPT Codes

11720CPT Code

Debridement of nails

Clinical Scenario

Used when significant nail debris is present and requires removal.

Documentation Requirements

Document the extent of debridement and the condition of the nail.

Specialty Considerations

Dermatology may require specific notes on the nail's appearance post-debridement.

ICD-10 Impact

Diagnostic & Documentation Impact

Enhanced Specificity

ICD-10 Improvements

The transition to ICD-10 has allowed for more specific coding of fungal infections, improving the accuracy of diagnosis and treatment tracking for conditions like tinea unguium.

ICD-9 vs ICD-10

The transition to ICD-10 has allowed for more specific coding of fungal infections, improving the accuracy of diagnosis and treatment tracking for conditions like tinea unguium.

Reimbursement & Billing Impact

The transition to ICD-10 has allowed for more specific coding of fungal infections, improving the accuracy of diagnosis and treatment tracking for conditions like tinea unguium.

Resources

Clinical References

  • •
    CDC Fungal Diseases

Coding & Billing References

  • •
    CDC Fungal Diseases

Frequently Asked Questions

What is the primary cause of tinea unguium?

Tinea unguium is primarily caused by dermatophytes, but can also be due to non-dermatophyte molds and yeasts.