2026 ICD-10-CM Diagnosis Code B35.9Dermatophytosis, unspecified

ICD-10-CM Codes›A00–B99›B35-B49›B35

ICD-10-CM B35.9
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

B35.9 is a billable ICD-10-CM diagnosis code for dermatophytosis, unspecified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 606 through 607. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Fungal infections.

Code Identity

ICD-10-CM Code
B35.9
Billable Status
Yes — Valid for Submission
Code Describes
Dermatophytosis, unspecified
Short Description
Dermatophytosis, unspecified
Same as the full description in the CMS dataset.
Parent Code
B35
Dermatophytosis

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionB35-B49Mycoses
CategoryB35Dermatophytosis
This CodeB35.9Dermatophytosis, unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Allergy-sensitivity to fungi syndrome
  • Dermatophytosis
  • Dermatophytosis caused by Microsporum praecox
  • Dermatophytosis co-occurrent with human immunodeficiency virus infection
  • Disseminated dermatophytosis
  • Disseminated dermatophytosis due to immunodeficiency
  • Favus caused by Trichophyton gallinae
  • Favus caused by Trichophyton schoenleinii
  • Id reaction
  • Steroid-modified tinea infection
  • Steroid-modified tinea infection of lower limb
  • Tinea caused by Epidermophyton floccosum
  • Tinea caused by Microsporum audouinii
  • Tinea caused by Microsporum canis variant canis
  • Tinea caused by Microsporum canis variant distortum
  • Tinea caused by Microsporum equinum
  • Tinea caused by Microsporum ferrugineum
  • Tinea caused by Microsporum nanum
  • Tinea caused by Microsporum vanbreuseghemii
  • Tinea caused by Nannizzia fulva
  • Tinea caused by Nannizzia gypsea
  • Tinea caused by Trichophyton
  • Tinea caused by Trichophyton concentricum
  • Tinea caused by Trichophyton equinum
  • Tinea caused by Trichophyton megninii
  • Tinea caused by Trichophyton mentagrophytes
  • Tinea caused by Trichophyton mentagrophytes variant erinacei
  • Tinea caused by Trichophyton mentagrophytes variant interdigitale
  • Tinea caused by Trichophyton persicolor
  • Tinea caused by Trichophyton rubrum
  • Tinea caused by Trichophyton simii
  • Tinea caused by Trichophyton soudanense
  • Tinea caused by Trichophyton tonsurans
  • Tinea caused by Trichophyton verrucosum
  • Tinea caused by Trichophyton violaceum
  • Tinea caused by Trichophyton yaoundei
  • Trichophytosis

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Ringworm NOS

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Dermatophytosis(epidermophyton) (infection) (Microsporum) (tinea) (Trichophyton)
    • Ringworm
    • Tinea(intersecta) (tarsi)

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR INF004
Fungal infections
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Deep Seated Dermatophytosis

    a deep folliculitis due to a cutaneous dermatophyte infection, usually on the legs. it is most commonly caused by trichophyton rubrum and is characterized by the formation of spongy granulomas which persist for three to four months and leaves deep scars.

  • Dermatophytosis

    a common fungal infection of the stratum corneum of the skin, hair, or nails by a dermatophyte. it is characterized by itching, inflammation, redness of the skin, small papular vesicles, central clearing, fissures, scaling, and/or hair loss in the affected area.

  • Dermatophytosis of Groin and Perianal Area

    dermatophytosis involving the stratum corneum of the skin of the groin and perianal area.

  • Dermatophytosis of Scalp and Beard

    dermatophytosis involving the stratum corneum of the skin of the scalp and beard area.

Patient EducationClinical

Fungal Infections

If you have ever had athlete's foot or a yeast infection, you can blame a fungus. A fungus is a primitive organism. Mushrooms, mold and mildew are examples. Fungi live in air, in soil, on plants and in water. Some live in the human body. Only about half of all types of fungi are harmful.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert B35.9 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
110.9 Dermatophytosis site NOS
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About B35.9Overview

Is B35.9 (Dermatophytosis) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report dermatophytosis, unspecified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does B35.9 group to?

When dermatophytosis, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 606, 607, with relative weights from 0.9064 to 1.5132 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of B35.9?

Under the General Equivalence Mappings, dermatophytosis, unspecified converts to ICD-9-CM 110.9 (dermatophytosis site NOS). The mapping is a direct match.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.