2026 ICD-10-CM Diagnosis Code J98.59Other diseases of mediastinum, not elsewhere classified

ICD-10-CM Codes›J00–J99›J96-J99›J98

ICD-10-CM J98.59
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

J98.59 is a billable ICD-10-CM diagnosis code for other diseases of mediastinum, not elsewhere classified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 177 through 179. Coders also document this condition as classical histoplasmosis mediastinal fibrosis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Mediastinal disorders.

Code Identity

ICD-10-CM Code
J98.59
Billable Status
Yes — Valid for Submission
Code Describes
Other diseases of mediastinum, not elsewhere classified
Short Description
Other diseases of mediastinum, not elsewhere classified
Same as the full description in the CMS dataset.
Parent Code
J98.5
Diseases of mediastinum, not elsewhere classified

Code Classification

ChapterJ00–J99Diseases of the respiratory system
SectionJ96-J99Other diseases of the respiratory system
CategoryJ98Other respiratory disorders
This CodeJ98.59Other diseases of mediastinum, not elsewhere classified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Classical histoplasmosis mediastinal fibrosis
  • Cyst of mediastinum
  • Disorder of mediastinum
  • Fibrosis of mediastinum
  • Hernia of mediastinum
  • Idiopathic hilar fibrosis
  • Mediastinal radiation fibrosis
  • Retraction of mediastinum
  • Widened mediastinum

Tabular List NotesGuidance

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

Inclusion Terms

  • Fibrosis of mediastinum
  • Hernia of mediastinum
  • Retraction of mediastinum

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.

    • Adhesions, adhesive(postinfective)
      • mediastinum
    • Disease, diseased
      • mediastinum
    • Fibrosis, fibrotic
      • mediastinum (idiopathic)
    • Hernia, hernial(acquired) (recurrent)
      • mediastinum
    • Herniation
      • mediastinum
    • Pressure
      • mediastinum
    • Retraction
      • mediastinum

Clinical ClassificationClinical

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

CCSR RSP015
Mediastinal disorders
Default principal diagnosis: inpatient Yes · outpatient Yes

Convert J98.59 to ICD-9-CMHistory

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

ICD-9-CM
519.3 Mediastinum disease NEC
Approximate The match is approximate rather than exact.

Code History & ChangesHistory

Replacement J98.59 replaces the following previously assigned code(s):

  • J98.5 - Diseases of mediastinum, not elsewhere classified
FY 2018AddedAdded to the ICD-10-CM code setEffective October 1, 2017.
FY 2019–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About J98.59Overview

Is J98.59 (Diseases of mediastinum, not elsewhere classified) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report other diseases of mediastinum, not elsewhere classified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does J98.59 group to?

When other diseases of mediastinum, not elsewhere classified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 177, 178, 179, with relative weights from 0.7550 to 1.5627 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of J98.59?

Under the General Equivalence Mappings, other diseases of mediastinum, not elsewhere classified converts to ICD-9-CM 519.3 (mediastinum disease NEC). 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.