2026 ICD-10-CM Diagnosis Code K65.4Sclerosing mesenteritis

ICD-10-CM Codes›K00–K95›K65-K68›K65

ICD-10-CM K65.4
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

K65.4 is a billable ICD-10-CM diagnosis code for sclerosing mesenteritis. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 393 through 395. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Peritonitis and intra-abdominal abscess.

Code Identity

ICD-10-CM Code
K65.4
Billable Status
Yes — Valid for Submission
Code Describes
Sclerosing mesenteritis
Short Description
Sclerosing mesenteritis
Same as the full description in the CMS dataset.
Parent Code
K65
Peritonitis

Code Classification

ChapterK00–K95Diseases of the digestive system
SectionK65-K68Diseases of peritoneum and retroperitoneum
CategoryK65Peritonitis
This CodeK65.4Sclerosing mesenteritis

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Aseptic peritonitis
  • Fat necrosis of peritoneum
  • Injury of omentum
  • Mesenteric fat necrosis
  • Mesenteric peritonitis with mesenteric fat necrosis
  • Omental fat necrosis
  • Retractile mesenteritis
  • Sclerosing mesenteritis
  • Sclerosing peritonitis
  • Serositis

Tabular List NotesGuidance

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

Inclusion Terms

  • Fat necrosis of peritoneum
  • (Idiopathic) sclerosing mesenteric fibrosis
  • Mesenteric lipodystrophy
  • Mesenteric panniculitis
  • Retractile mesenteritis

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.

    • Fat
      • necrosis
        • mesentery
    • Fat
      • necrosis
        • omentum
    • Fibrosis, fibrotic
      • sclerosing mesenteric (idiopathic)
    • Lipodystrophy
      • mesenteric
    • Mesenteritis
      • retractile
    • Mesenteritis
      • sclerosing
    • Necrosis, necrotic(ischemic)
      • fat, fatty (generalized)
        • abdominal wall
    • Necrosis, necrotic(ischemic)
      • fat, fatty (generalized)
        • mesentery
    • Necrosis, necrotic(ischemic)
      • fat, fatty (generalized)
        • omentum
    • Necrosis, necrotic(ischemic)
      • fat, fatty (generalized)
        • peritoneum
    • Necrosis, necrotic(ischemic)
      • mesentery
        • fat
    • Necrosis, necrotic(ischemic)
      • omentum (with mesenteric infarction)
        • fat
    • Necrosis, necrotic(ischemic)
      • peritoneum (with mesenteric infarction)
        • fat
    • Panniculitis(nodular) (nonsuppurative)
      • mesenteric

Clinical ClassificationClinical

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

CCSR DIG016
Peritonitis and intra-abdominal abscess
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Serositis

    inflammation of a serous membrane.

  • Ovarian Luteinized Thecoma Associated with Sclerosing Peritonitis

    a rare usually bilateral luteinized thecoma that arises from the ovary and is associated with sclerosing peritonitis. it occurs mostly in premenopausal women. the ovarian tumor is benign but patients may develop intestinal obstruction due to the sclerosing peritonitis.

  • Sclerosing Peritonitis

    a rare peritoneal cavity disorder that is characterized by the development of dense fibrous tissue in the peritoneum and the creation of severe adhesions in the abdomen that result in partial or complete small bowel obstruction. it may be idiopathic or develop in patients who receive peritoneal dialysis treatment. patients present with abdominal distention and pain.

Patient EducationClinical

Peritoneal Disorders

Your peritoneum is the tissue that lines your abdominal wall and covers most of the organs in your abdomen. A liquid, peritoneal fluid, lubricates the surface of this tissue.

Read the full article at MedlinePlus

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

Convert K65.4 to ICD-9-CMHistory

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

ICD-9-CM
567.82 Sclerosing mesenteritis
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 K65.4Overview

Is K65.4 (Peritonitis) a billable code?

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

What MS-DRG does K65.4 group to?

When sclerosing mesenteritis is the principal diagnosis on an inpatient stay, it groups to MS-DRG 393, 394, 395, with relative weights from 0.6490 to 1.5993 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of K65.4?

Under the General Equivalence Mappings, sclerosing mesenteritis converts to ICD-9-CM 567.82 (sclerosing mesenteritis). 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.