J98.59
Other diseases of mediastinum, not elsewhere classified
J98.59 (also written J9859) is a billable ICD-10-CM diagnosis code for other diseases of mediastinum, not elsewhere classified. It is part of the FY2027 code set, effective October 1, 2026. It is one of the 12 codes in category J98 (Other respiratory disorders). The Alphabetic Index lists it under 7 entries. Its coding notes include a Use additional code instruction, 2 Excludes1 entries and 12 Excludes2 entries.
Use additional code
Add the listed code as a secondary code, if known.
Also from chapter/block level (7 notes)
Excludes1
Not coded here. The listed conditions generally should not be reported together.
Excludes2
Not included here. Both codes may be reported if the patient has both conditions.
- abscess of mediastinum (J85.3)
Also from chapter/block level (9 notes)
- certain conditions originating in the perinatal period (P04-P96)
- certain infectious and parasitic diseases (A00-B99)
- complications of pregnancy, childbirth and the puerperium (O00-O9A)
- congenital malformations, deformations and chromosomal abnormalities (Q00-Q99)
- endocrine, nutritional and metabolic diseases (E00-E88)
- injury, poisoning and certain other consequences of external causes (S00-T88)
- neoplasms (C00-D49)
- smoke inhalation (T59.81-)
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
Care settings
How CMS programs treat this code. These are CMS claim edits and list entries, not coverage or eligibility rules.
Home Health Primary
Accepted as the primary (principal) diagnosis on a home health claim. The Home Health Grouper assigns it to the MMTA - Respiratory clinical group.
Source: CMS Home Health Grouper Software v07.2.26, effective October 1, 2026Hospital MCC
Counts as a major complication or comorbidity (MCC) when reported as a secondary diagnosis on an inpatient claim. It does not count when the principal diagnosis is one of the 1 code in its exclusion list. Some MS-DRGs also ignore a CC or MCC that defines the DRG.
Source: CMS MS-DRG Definitions Manual v44, effective October 1, 2026, Appendix CHAC
On the CMS list of hospital-acquired conditions (HAC 08: Surgical Site Infection-Mediastinitis After Coronary Bypass Graft (CABG)). When the claim reports it with a present-on-admission (POA) indicator of N (not present) or U (documentation insufficient), CMS does not pay the CC or MCC DRG for it. A POA of Y (present) or W (clinically undetermined) is paid normally. Some HAC categories also require a listed procedure.
Source: CMS MS-DRG Definitions Manual v44, effective October 1, 2026, Appendix I; CMS Hospital-Acquired Conditions (HAC) Coding page, POA indicator payment tableInclusion terms
Conditions classified to this code.
- Fibrosis of mediastinum
- Hernia of mediastinum
- Retraction of mediastinum
Notes
Also from chapter/block level (1 note)
- When a respiratory condition is described as occurring in more than one site and is not specifically indexed, it should be classified to the lower anatomic site (e.g. tracheobronchitis to bronchitis in J40).
Alphabetic Index terms
Terms the official Alphabetic Index lists for this code. 7 entries