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ICD-10 Guide
ICD-10 CodesChapter 1: Certain infectious and parasitic diseasesB35.2

B35.2

Billable

Tinea unguium

Chapter 1:Certain infectious and parasitic diseases

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

Code Description

ICD-10 B35.2 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, primarily the toenails but can also involve fingernails. It is characterized by nail discoloration, thickening, and potential separation from the nail bed. The infection is often caused by dermatophytes, but non-dermatophyte molds and yeasts can also be responsible. 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, which are more effective for extensive infections. 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
  • Understanding the various treatment options and their indications
  • Recognizing the impact of comorbidities on treatment efficacy
  • Navigating documentation requirements for antifungal therapies

Audit Risk Factors

  • Inadequate documentation of the diagnosis
  • Failure to document the patient's immunocompromised status
  • Lack of evidence for treatment choice
  • Incorrect coding of associated conditions

Specialty Focus

Medical Specialties

Dermatology

Documentation Requirements

Detailed clinical notes including symptoms, duration, and treatment response.

Common Clinical Scenarios

Patients presenting with nail changes, recurrent fungal infections, or treatment failures.

Billing Considerations

Consideration of nail biopsy for definitive diagnosis in atypical cases.

Infectious Disease

Documentation Requirements

Comprehensive history of immunocompromised conditions and previous treatments.

Common Clinical Scenarios

Management of onychomycosis in patients with HIV/AIDS or undergoing chemotherapy.

Billing Considerations

Close monitoring of treatment response and potential drug interactions.

Coding Guidelines

Inclusion Criteria

Use B35.2 When
  • Follow the official ICD
  • CM coding guidelines, ensuring accurate documentation of the diagnosis and any associated conditions
  • Include details on the site of infection and any relevant comorbidities

Exclusion Criteria

Do NOT use B35.2 When
No specific exclusions found.

Related ICD-10 Codes

Related CPT Codes

11720CPT Code

Debridement of nails

Clinical Scenario

Used when extensive debridement is necessary for treatment of onychomycosis.

Documentation Requirements

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

Specialty Considerations

Dermatologists may perform this procedure more frequently.

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 caused by non-dermatophyte molds and yeasts.