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ICD-10 Guide
ICD-10 CodesB46.1

B46.1

Tinea unguium

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

Code Description

ICD-10 B46.1 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 potential separation of the nail from the nail bed. The condition is primarily caused by dermatophytes, but can also be due to non-dermatophyte molds and yeasts. Risk factors include advanced age, diabetes mellitus, immunocompromised states, and poor circulation. 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 or scrapings sent for fungal culture or microscopy. Treatment options include topical antifungals like ciclopirox and systemic antifungals such as terbinafine and itraconazole. In immunocompromised patients, the infection may be more severe and resistant to treatment, necessitating a more aggressive therapeutic approach. Regular follow-up is essential to monitor treatment efficacy and prevent recurrence.

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
  • Navigating documentation requirements for antifungal therapies

Audit Risk Factors

  • Inadequate documentation of the diagnosis
  • Failure to specify the type of antifungal treatment administered
  • Misclassification of the patient's immune status
  • Lack of follow-up documentation

Specialty Focus

Medical Specialties

Dermatology

Documentation Requirements

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

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, treatment response, and any secondary infections.

Common Clinical Scenarios

Immunocompromised patients with recurrent or severe fungal infections.

Billing Considerations

Document the patient's immune status and any complications arising from the infection.

Coding Guidelines

Inclusion Criteria

Use B46.1 When
  • Follow the official ICD
  • CM coding guidelines, ensuring accurate documentation of the diagnosis, treatment, and any comorbidities
  • Include details on the patient's immune status and the specific antifungal treatments used

Exclusion Criteria

Do NOT use B46.1 When
No specific exclusions found.

Related CPT Codes

11720CPT Code

Debridement of nails

Clinical Scenario

Used when extensive nail debridement is necessary due to fungal infection.

Documentation Requirements

Document the extent of debridement and the reason for the procedure.

Specialty Considerations

Dermatologists should ensure proper coding for debridement procedures.

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 diagnoses 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 diagnoses 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 diagnoses 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 dermatophyte fungi, but can also be due to non-dermatophyte molds and yeasts.

How is tinea unguium diagnosed?

Diagnosis is made through clinical examination and confirmed by laboratory tests such as nail clippings or scrapings sent for fungal culture or microscopy.

What are the treatment options for tinea unguium?

Treatment options include topical antifungals like ciclopirox and systemic antifungals such as terbinafine and itraconazole.