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ICD-10 Guide
ICD-10 CodesChapter 1: Certain infectious and parasitic diseasesB35.1

B35.1

Billable

Tinea unguium

Chapter 1:Certain infectious and parasitic diseases

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

Code Description

ICD-10 B35.1 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 and fingernails. It is primarily caused by dermatophytes, but can also be due to non-dermatophyte molds and yeasts. The infection typically presents as discoloration, thickening, and separation of the nail from the nail bed, leading to potential pain and discomfort. The condition is more prevalent in individuals with compromised immune systems, diabetes, or peripheral vascular disease. Diagnosis is often made through clinical examination and confirmed with laboratory tests such as nail clippings or scrapings sent for fungal culture or microscopy. Treatment options include topical antifungal agents like ciclopirox and systemic antifungals such as terbinafine or itraconazole, which are more effective for extensive infections. Given the chronic nature of tinea unguium, treatment may require several months, and adherence to therapy is crucial for successful outcomes. Patients with immunocompromised states may experience more severe manifestations and require closer monitoring and aggressive treatment strategies.

Code Complexity Analysis

Complexity Rating: Medium

Medium Complexity

Complexity Factors

  • Differentiating between types of fungal infections
  • Variability in treatment regimens based on patient health status
  • Need for laboratory confirmation in some cases
  • Potential for co-existing conditions affecting treatment

Audit Risk Factors

  • Inadequate documentation of the diagnosis
  • Failure to document the type of antifungal treatment prescribed
  • Lack of follow-up notes on treatment efficacy
  • Misclassification of the infection type

Specialty Focus

Medical Specialties

Dermatology

Documentation Requirements

Detailed clinical notes on the appearance of the nails, history of symptoms, and any previous treatments.

Common Clinical Scenarios

Patients presenting with nail discoloration, thickening, or pain; recurrent infections.

Billing Considerations

Consideration of patient history, including immunocompromised status and previous antifungal treatments.

Podiatry

Documentation Requirements

Foot examination findings, patient history regarding foot care, and any systemic conditions.

Common Clinical Scenarios

Patients with diabetes or peripheral vascular disease presenting with nail issues.

Billing Considerations

Importance of documenting vascular status and any foot complications.

Coding Guidelines

Inclusion Criteria

Use B35.1 When
  • According to ICD
  • 10 guidelines, B35
  • 1 should be used when the fungal infection is confirmed and documented
  • It is important to note the specific type of fungus if known and to document any relevant comorbidities

Exclusion Criteria

Do NOT use B35.1 When
No specific exclusions found.

Related ICD-10 Codes

Related CPT Codes

11730CPT Code

Removal of nail plate

Clinical Scenario

Used when extensive nail involvement requires surgical intervention.

Documentation Requirements

Document the reason for nail removal and any associated procedures.

Specialty Considerations

Podiatrists may frequently perform this procedure in cases of severe onychomycosis.

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 data collection 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 data collection 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 data collection and treatment tracking for conditions like tinea unguium.

Resources

Clinical References

  • •
    CDC - Fungal Diseases

Coding & Billing References

  • •
    CDC - Fungal Diseases

Frequently Asked Questions

What are the common treatments for tinea unguium?

Common treatments include topical antifungals like ciclopirox and systemic antifungals such as terbinafine and itraconazole, depending on the severity of the infection.

How can I differentiate tinea unguium from other nail conditions?

Tinea unguium typically presents with nail discoloration, thickening, and separation from the nail bed. Laboratory tests can confirm the diagnosis.