2026 ICD-10-CM Diagnosis Code L04.9Acute lymphadenitis, unspecified

ICD-10-CM Codes›L00–L99›L00-L08›L04

ICD-10-CM L04.9
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

L04.9 is a billable ICD-10-CM diagnosis code for acute lymphadenitis, unspecified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 814 through 816. Coders also document this condition as acute abscess lymph node. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Skin and subcutaneous tissue infections.

Code Identity

ICD-10-CM Code
L04.9
Billable Status
Yes — Valid for Submission
Code Describes
Acute lymphadenitis, unspecified
Short Description
Acute lymphadenitis, unspecified
Same as the full description in the CMS dataset.
Parent Code
L04
Acute lymphadenitis

Code Classification

ChapterL00–L99Diseases of the skin and subcutaneous tissue
SectionL00-L08Infections of the skin and subcutaneous tissue
CategoryL04Acute lymphadenitis
This CodeL04.9Acute lymphadenitis, unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acute abscess lymph node
  • Acute HIV infection
  • Acute lymphadenitis
  • HIV infection with acute lymphadenitis
  • Infected lymphocele
  • Lymph node abscess
  • Lymphadenopathy co-occurrent with human immunodeficiency virus infection
  • Lymphocele
  • Suppurative lymphadenopathy

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.

    • Adenitis
      • acute, unspecified site
    • Adenitis
      • gangrenous
    • Lymphadenitis
      • acute

Clinical ClassificationClinical

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

CCSR SKN001
Skin and subcutaneous tissue infections
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Lymphocele

    cystic mass containing lymph from diseased lymphatic channels or following surgical trauma or other injury.

  • Acute Lymphadenitis

    acute inflammation of the lymph nodes.

  • Grade 1 Lymphocele, CTCAE|Grade 1 Lymphocele|Grade 1 Lymphocele

    asymptomatic; clinical or diagnostic observations only; intervention not indicated

  • Grade 2 Lymphocele, CTCAE|Grade 2 Lymphocele|Grade 2 Lymphocele

    symptomatic; medical intervention indicated

  • Grade 3 Lymphocele, CTCAE|Grade 3 Lymphocele|Grade 3 Lymphocele

    severe symptoms; invasive intervention indicated

  • Lymphocele

    a cystic lesion containing lymph. it usually results from injury, gynecologic surgery, or urologic surgery.

  • Lymphocele, CTCAE|Lymphocele|Lymphocele|Lymphocele

    a disorder characterized by a cystic lesion containing lymph.

  • Microsphere-Mediated Lymphocele Prevention

    a surgical technique that uses microspheres at the site of a lymph node resection in an effort to prevent the formation of a lymphocele.

  • Renal Lymphocele|Kidney Lymphocele|Kidney Lymphocele

    encapsulated collection of lymphatic fluid around a transplanted kidney.

  • Lymph Node Abscess

    an abscess that develops in a lymph node and the surrounding tissues as a result of an infectious process. the affected lymph node is palpable and tender.

Patient EducationClinical

Lymphatic Diseases

The lymphatic system is a network of tissues and organs. It is made up of:

Read the full article at MedlinePlus

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

Convert L04.9 to ICD-9-CMHistory

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

ICD-9-CM
683 Acute lymphadenitis
Approximate The match is approximate rather than exact.

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 L04.9Overview

Is L04.9 (Acute lymphadenitis) a billable code?

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

What MS-DRG does L04.9 group to?

When acute lymphadenitis, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 814, 815, 816, with relative weights from 0.6320 to 2.1267 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of L04.9?

Under the General Equivalence Mappings, acute lymphadenitis, unspecified converts to ICD-9-CM 683 (acute lymphadenitis). The mapping is approximate, so confirm the match fits the documentation.

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.