2026 ICD-10-CM Diagnosis Code B97.33Human T-cell lymphotrophic virus, type I [HTLV-I] as the cause of diseases classified elsewhere

ICD-10-CM Codes›A00–B99›B95-B97›B97

ICD-10-CM B97.33
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

B97.33 is a billable ICD-10-CM diagnosis code for human T-cell lymphotrophic virus, type I [HTLV-I] as the cause of diseases classified elsewhere. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 865 through 866. The code is not accepted as a principal diagnosis by the Medicare Code Editor. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Viral infection.

Code Identity

ICD-10-CM Code
B97.33
Billable Status
Yes — Valid for Submission
Code Describes
Human T-cell lymphotrophic virus, type I [HTLV-I] as the cause of diseases classified elsewhere
Short Description
HTLV-I as the cause of diseases classified elsewhere
Parent Code
B97.3
Retrovirus as the cause of diseases classified elsewhere

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionB95-B97Bacterial and viral infectious agents
CategoryB97Viral agents as the cause of diseases classified elsewhere
This CodeB97.33Human T-cell lymphotrophic virus, type I [HTLV-I] as the cause of diseases classified elsewhere

Code EditsBilling

Medicare Code Editor checks that affect claim validity for B97.33.

Unacceptable principal diagnosis
There are selected codes that describe a circumstance which influences an individual's health status but not a current illness or injury, or codes that are not specific manifestations but may be due to an underlying cause. These codes are considered unacceptable as a principal diagnosis.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Disease caused by Deltaretrovirus
  • Human T-cell Lymphoma Virus Type -1 associated uveitis
  • Human T-cell lymphotropic virus 1-associated myelopathy
  • Human T-lymphotropic virus 1 infection
  • Human T-lymphotropic virus 2 infection
  • Human T-lymphotropic virus type 1 encephalitis
  • Infected eczema
  • Infection caused by Human T-lymphotropic virus
  • Infectious eczematoid dermatitis
  • Infective dermatitis associated with human T-cell lymphotropic virus 1 infection
  • Myelitis caused by human T-lymphotropic virus type 1
  • Myelitis caused by Retroviridae
  • Retroviridae encephalitis

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.

    • Human
      • T-cell lymphotropic virus
        • type-1 (HTLV-I) infection
          • as cause of disease classified elsewhere
    • Infection, infected, infective(opportunistic)
      • retrovirus
        • as cause of disease classified elsewhere
          • human
            • T-cell lymphotropic
              • type I (HTLV-I)
    • Infection, infected, infective(opportunistic)
      • virus, viral NOS
        • as cause of disease classified elsewhere
          • human
            • T-cell lymphotropic,
              • type I (HTLV-I)
    • Infection, infected, infective(opportunistic)
      • virus, viral NOS
        • as cause of disease classified elsewhere
          • retrovirus
            • human
              • T-cell lymphotropic,
                • type I (HTLV-I)
    • Retrovirus, as cause of disease classified elsewhere
      • human
        • T-cell lymphotropic
          • type I (HTLV-I)

Clinical ClassificationClinical

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

CCSR INF008
Viral infection
Default principal diagnosis: inpatient No · outpatient No

Patient EducationClinical

Viral Infections

Viruses are very tiny germs. They are made of genetic material (either DNA or RNA) inside of a protein coating. There are a huge number of viruses on earth. Only a small number of them can infect humans. Those viruses can infect our cells, which may cause disease.

The full article covers:

  • What are viruses?
  • How are viruses spread?
  • How do viruses cause disease?
  • What are the treatments for viral infections?
  • Can viral infections be prevented?

Read the full article at MedlinePlus

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

Convert B97.33 to ICD-9-CMHistory

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

ICD-9-CM
079.51 Htlv-1 infection oth dis
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 B97.33Overview

Is B97.33 (Retrovirus as the cause of diseases classified elsewhere) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report human T-cell lymphotrophic virus, type I [HTLV-I] as the cause of diseases classified elsewhere on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does B97.33 group to?

On inpatient claims, human T-cell lymphotrophic virus, type I [HTLV-I] as the cause of diseases classified elsewhere maps to MS-DRG 865, 866, with relative weights from 0.8696 to 1.4983 depending on complications. Higher weights mean higher Medicare reimbursement.

Can B97.33 be a principal diagnosis?

No. The Medicare Code Editor rejects this code as a principal diagnosis because human T-cell lymphotrophic virus, type I [HTLV-I] as the cause of diseases classified elsewhere describes a circumstance that influences health status rather than a current illness. Report it as a secondary diagnosis.

What is the ICD-9 equivalent of B97.33?

Under the General Equivalence Mappings, human T-cell lymphotrophic virus, type I [HTLV-I] as the cause of diseases classified elsewhere converts to ICD-9-CM 079.51 (Htlv-1 infection oth dis). 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.