2026 ICD-10-CM Diagnosis Code A55Chlamydial lymphogranuloma (venereum)

ICD-10-CM Codes›A00–B99›A50-A64›venereum

ICD-10-CM A55
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

A55 is a billable ICD-10-CM diagnosis code for chlamydial lymphogranuloma (venereum). It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 727 through 728, 742 through 743, 757 through 759. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Sexually transmitted infections (excluding HIV and hepatitis).

Code Identity

ICD-10-CM Code
A55
Billable Status
Yes — Valid for Submission
Code Describes
Chlamydial lymphogranuloma (venereum)
Chapter
A50-A64
Infections with a predominantly sexual mode of transmission

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionA50-A64Infections with a predominantly sexual mode of transmission
CategoryvenereumChlamydial lymphogranuloma (A55)
This CodeA55Chlamydial lymphogranuloma (venereum)

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Chronic acquired lymphedema
  • Chronic disease of lymphatic vessels
  • Early lymphogranuloma venereum
  • Esthiomene
  • Infection of skin caused by Chlamydia
  • Infectious edema
  • Late lymphogranuloma venereum
  • Latent lymphogranuloma venereum
  • Lymphedema due to infection
  • Lymphedema due to lymphogranuloma venereum
  • Lymphogranuloma venereum
  • Venereal disease caused by Chlamydia trachomatis

Tabular List NotesGuidance

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

Inclusion Terms

  • Climatic or tropical bubo
  • Durand-Nicolas-Favre disease
  • Esthiomene
  • Lymphogranuloma inguinale

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.

    • Bubo
      • climatic
    • Bubo
      • inguinal (nonspecific)
        • climatic
    • Bubo
      • tropical
    • Disease, diseased
      • Durand-Nicholas-Favre (climatic bubo)
    • Disease, diseased
      • Favre-Durand-Nicolas (climatic bubo)
    • Disease, diseased
      • Frei's (climatic bubo)
    • Disease, diseased
      • Nicolas (-Durand)-Favre (climatic bubo)
    • Disease, diseased
      • venereal
        • fifth
    • Disease, diseased
      • venereal
        • sixth
    • Durand-Nicolas-Favre disease
    • Esthiomene
    • Fifth disease
      • venereal
    • Frei's disease
    • Genito-anorectal syndrome
    • Infection, infected, infective(opportunistic)
      • Chlamydia, chlamydial
        • lymphogranuloma
    • Lymphadenitis
      • due to
        • chlamydial lymphogranuloma
    • Lymphadenitis
      • due to
        • lymphogranuloma venereum
    • Lymphadenitis
      • venereal (chlamydial)
    • Lymphogranuloma(malignant)
      • chlamydial
    • Lymphogranuloma(malignant)
      • inguinale
    • Lymphogranuloma(malignant)
      • venereum (any site) (chlamydial) (with stricture of rectum)
    • Lymphopathia venereum, veneris
    • Nicolas(-Durand)-Favre disease
    • Poradenitis, nostras inguinalis or venerea
    • Stricture
      • rectum (sphincter)
        • due to
          • chlamydial lymphogranuloma
    • Stricture
      • rectum (sphincter)
        • due to
          • lymphogranuloma venereum
    • Stricture
      • rectum (sphincter)
        • inflammatory (chlamydial)
    • Syndrome
      • genito-anorectal
    • Venereal
      • bubo
    • Venereal
      • lymphogranuloma (Durand-Nicolas-Favre)

Clinical ClassificationClinical

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

CCSR INF010
Sexually transmitted infections (excluding HIV and hepatitis)
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Lymphogranuloma Venereum

    subacute inflammation of the inguinal lymph glands caused by certain immunotypes of chlamydia trachomatis. it is a sexually transmitted disease in the u.s. but is more widespread in developing countries. it is distinguished from granuloma venereum (see granuloma inguinale), which is caused by calymmatobacterium granulomatis.

  • Lymphogranuloma Venereum

    infection with the organism mycobacterium.

Patient EducationClinical

Chlamydia Infections

Chlamydia is a common sexually transmitted infection (STI). It is caused by bacteria called Chlamydia trachomatis. Anyone can get chlamydia. It often doesn't cause symptoms, so people may not know that they have it. Antibiotics can cure it. But if it's not treated, chlamydia can cause serious health problems.

The full article covers:

  • What is chlamydia?
  • How is chlamydia spread?
  • Who is more likely to get chlamydia?
  • What are the symptoms of chlamydia?
  • How is chlamydia diagnosed?
  • Who should be tested for chlamydia?
  • What other problems can chlamydia cause?
  • What are the treatments for chlamydia?

Read the full article at MedlinePlus

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

Convert A55 to ICD-9-CMHistory

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

ICD-9-CM
099.1 Lymphogranuloma venereum
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 A55Overview

Is A55 (Chlamydial lymphogranuloma (venereum)) a billable code?

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

What MS-DRG does A55 group to?

When chlamydial lymphogranuloma (venereum) is the principal diagnosis on an inpatient stay, it groups to MS-DRG 727, 728, 742, 743, 757, 758, 759, with relative weights from 0.6636 to 1.8348 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of A55?

Under the General Equivalence Mappings, chlamydial lymphogranuloma (venereum) converts to ICD-9-CM 099.1 (lymphogranuloma venereum). 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.