2026 ICD-10-CM Diagnosis Code L03.91Acute lymphangitis, unspecified
ICD-10-CM Codes›L00–L99›L00-L08›L03
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Not Chronic
L03.91 is a billable ICD-10-CM diagnosis code for acute lymphangitis, unspecified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 573 through 575, 602 through 603, 791, 793. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 43 closely related codes. Coders also document this condition as acute lymphangitis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Skin and subcutaneous tissue infections.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Acute lymphangitis
- Acute lymphangitis caused by bacterium
- Acute lymphangitis of skin excluding digits of hand or foot
- Cellulitis with lymphangitis of digit
- Infectious lymphangitis
- Infectious lymphangitis of deep lymphatics
- Infectious lymphangitis of superficial lymphatics
- Lymphangitis caused by bacterium
Tabular List NotesGuidance
Coding notes and annotation back-references applicable to this code.
Type 1 Excludes
- lymphangitis NOS I89.1
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
acute L03.91
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Bacterial Infections
Bacteria are tiny organisms (living things) that have only one cell. Under a microscope, they look like balls, rods, or spirals. They can be found almost everywhere on Earth. There are lots of bacteria in and on your body. In fact, your body has about 10 times more bacteria cells than human cells.
The full article covers:
- What are bacteria?
- How do bacterial infections spread?
- What are the treatments for bacterial infections?
- Can bacterial infections be prevented?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert L03.91 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About L03.91Overview
What is the ICD-10 code for acute lymphangitis, unspecified?
The ICD-10-CM code for acute lymphangitis, unspecified is L03.91 (sometimes written as L0391). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is L03.91 (Cellulitis and acute lymphangitis, unspecified) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report acute lymphangitis, unspecified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does L03.91 group to?
When acute lymphangitis, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 573, 574, 575, 602, 603, 791, 793, with relative weights from 0.8709 to 6.5514 depending on complications. Higher weights mean higher Medicare reimbursement.
Is L03.91 a CC or MCC?
CMS lists L03.91 as a CC (complication or comorbidity) for FY 2026. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 43 closely related codes in its exclusion list.
What is the ICD-9 equivalent of L03.91?
Under the General Equivalence Mappings, acute lymphangitis, unspecified converts to ICD-9-CM 682.9 (cellulitis NOS). The mapping is approximate, so confirm the match fits the documentation.
