2026 ICD-10-CM Diagnosis Code L03.312Cellulitis of back [any part except buttock]

ICD-10-CM Codes›L00–L99›L00-L08›L03

ICD-10-CM L03.312
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

L03.312 is a billable ICD-10-CM diagnosis code for cellulitis of back [any part except buttock]. 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. Coders also document this condition as abscess of flank. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Skin and subcutaneous tissue infections.

Code Identity

ICD-10-CM Code
L03.312
Billable Status
Yes — Valid for Submission
Code Describes
Cellulitis of back [any part except buttock]
Short Description
Cellulitis of back [any part except buttock]
Same as the full description in the CMS dataset.
Parent Code
L03.31
Cellulitis of trunk

Code Classification

ChapterL00–L99Diseases of the skin and subcutaneous tissue
SectionL00-L08Infections of the skin and subcutaneous tissue
CategoryL03Cellulitis and acute lymphangitis
This CodeL03.312Cellulitis of back [any part except buttock]

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Abscess of flank
  • Cellulitis and abscess of back
  • Cellulitis and abscess of flank
  • Cellulitis and abscess of trunk
  • Cellulitis of flank
  • Cellulitis of skin of back

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.

    • Cellulitis(diffuse) (phlegmonous) (septic) (suppurative)
      • back (any part)
    • Cellulitis(diffuse) (phlegmonous) (septic) (suppurative)
      • trunk
        • back (any part)

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

Patient EducationClinical

Cellulitis

Cellulitis is an infection of the skin and deep underlying tissues. Group A strep (streptococcal) bacteria are the most common cause. The bacteria enter your body when you get an injury such as a bruise, burn, surgical cut, or wound.

Read the full article at MedlinePlus

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

Convert L03.312 to ICD-9-CMHistory

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

ICD-9-CM
682.2 Cellulitis of trunk
Approximate The match is approximate rather than exact.

Code History & ChangesHistory

Replaced This code was replaced in the FY 2026 code set by:

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 L03.312Overview

Is L03.312 (Cellulitis of trunk) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report cellulitis of back [any part except buttock] on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does L03.312 group to?

When cellulitis of back [any part except buttock] is the principal diagnosis on an inpatient stay, it groups to MS-DRG 573, 574, 575, 602, 603, with relative weights from 0.8709 to 6.5514 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of L03.312?

Under the General Equivalence Mappings, cellulitis of back [any part except buttock] converts to ICD-9-CM 682.2 (cellulitis of trunk). 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.