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ICD-10-CM 2027 diagnosis code

M65.98Unspecified synovitis and tenosynovitis, other site

✓ Billable / specific

M65.98 is a valid, billable ICD-10-CM code for unspecified synovitis and tenosynovitis, other site. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.

Code last changed in FY2025 (effective October 1, 2024). Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About M65.98

M65.98 is the ICD-10-CM diagnosis code for unspecified synovitis and tenosynovitis, other site. It belongs to category M65 (synovitis and tenosynovitis), block M65-M67 (disorders of synovium and tendon) and chapter 13 (diseases of the musculoskeletal system and connective tissue). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within M65.9, choose M65.98 (other site) only when documentation doesn't support a more specific option: unspecified site (M65.90), shoulder (M65.91), upper arm (M65.92), forearm (M65.93), hand (M65.94), thigh (M65.95), lower leg (M65.96), ankle and foot (M65.97) and 1 more.

It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.

In MS-DRG v44.0, it is part of the grouping logic for DRG 557 (Tendonitis, Myositis and Bursitis with MCC, relative weight 1.489) and DRG 558 (Tendonitis, Myositis and Bursitis without MCC, relative weight 0.8875), in MDC 08 (Diseases and Disorders of the Musculoskeletal System and Connective Tissue), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It was added in FY2025, effective October 1, 2024.

Notes that apply from higher levels

Instructions written at a parent level also apply to M65.98.

› From M65 Synovitis and tenosynovitis
Excludes1
  • chronic crepitant synovitis of hand and wrist (M70.0-)
  • current injury - see injury of ligament or tendon by body region
  • soft tissue disorders related to use, overuse and pressure (M70.-)

Broader instructions also apply from Chapter 13: Diseases of the musculoskeletal system and connective tissue.

Alphabetic index entries

1 entries

Terms in the official ICD-10-CM index that lead to M65.98.

MS-DRG v44.0 grouping

All DRGs →

Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.

MDC 08 · Diseases and Disorders of the Musculoskeletal System and Connective Tissue

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2025 (effective 10/1/2024): Added
  • No changes since FY2025.

Common questions about M65.98

Is M65.98 billable?

Yes. M65.98 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can M65.98 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict M65.98 as a principal diagnosis.

Is M65.98 a CC or MCC?

No. M65.98 is neither a CC nor an MCC under MS-DRG v44.0.

What DRG does M65.98 group to?

M65.98 is used in the MS-DRG v44.0 logic for MS-DRG 557 (Tendonitis, Myositis and Bursitis with MCC) and MS-DRG 558 (Tendonitis, Myositis and Bursitis without MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.