ICD-10-CM · Other

M12.38

Palindromic rheumatism affecting a specified joint site that does not correspond to any other individually enumerated site in the M12.3 subcategory — most notably used for vertebral involvement per the ICD-10-CM tabular note.

Verified May 8, 2026 · 5 sources ↓

Status: Billable
Chapter: 13
Related CPT: 5
Region: Other

Drawn from CDCAAPCCMSICD10Data

Documentation tips

What should appear in the chart to support M12.38.

Source · Editorial brief grounded in 5 cited references ↓

Document the specific joint site by name (e.g., 'vertebral,' 'sternoclavicular,' 'temporomandibular') — 'other specified site' requires that the site be named in the note even though it doesn't appear in the code descriptor.
Record the episodic, self-limiting pattern: onset, duration of flare, and complete resolution between attacks — this clinical pattern is what distinguishes palindromic rheumatism from other inflammatory arthropathies.
Note any imaging findings (plain film, MRI) at the affected site, especially for vertebral involvement, to support medical necessity and differentiate from degenerative disc disease or spondyloarthropathy.
If the patient is being evaluated for possible progression to rheumatoid arthritis, document serologic findings (RF, anti-CCP) and capture any concurrent RA code separately if RA criteria are met.
Confirm and document that arthrosis (osteoarthritis) has been excluded at the same site — the M12 Excludes1 note prohibits coding M12.38 alongside M15–M19 for the same joint.

Related CPT procedures

Procedure codes commonly billed with M12.38. Linking the right diagnosis to the right procedure is what establishes medical necessity.

Source · CMS LCDs · AAOS specialty guidance · claims-pattern analysis

99213 $95.19

Established patient office or outpatient visit requiring 20–29 minutes of total time or low-complexity medical decision-making.

99214 $135.61

Office visit for an established patient requiring moderate-complexity medical decision making (MDM), or 30–39 minutes of total provider time on the date of service.

99215 $192.39

Highest-level office or outpatient E/M visit for an established patient, qualifying via high-complexity medical decision making or 40–54 minutes of total provider time on the date of service.

20610 $68.81

Aspiration and/or injection of a major joint or bursa (shoulder, hip, knee, or subacromial bursa) performed without ultrasound guidance.

72148 $191.72

Non-contrast MRI of the lumbar spine used to evaluate disc pathology, spinal stenosis, nerve root compression, and other structural abnormalities without administration of contrast material.

Common coding pitfalls

The recurring mistakes coders make with M12.38 and adjacent codes.

Source · Editorial brief grounded in CDC ICD-10-CM tabular guidance, AAOS coding references, and cited references ↓

Using M12.38 for peripheral joints that have their own site-specific codes — shoulder (M12.31x), hip (M12.35x), knee (M12.36x), and ankle/foot (M12.37x) all have dedicated codes; M12.38 is only correct when the site genuinely lacks a specific code.
Confusing 'other specified site' with 'unspecified site' — if the clinician documents a specific joint, do not default to M12.30 (unspecified); conversely, if no site is documented at all, M12.38 is not appropriate.
Coding M12.38 alongside an arthrosis code (M15–M19) for the same joint violates the M12 Excludes1 instruction; if both conditions are present at different sites, code each site separately with the correct code.
Selecting M12.38 when multiple joints are affected across different sites — use M12.39 (multiple sites) instead when the note describes palindromic involvement at several distinct joints in the same encounter.

Clinical context

Source · Editorial summary grounded in 5 cited references ↓

M12.38 captures palindromic rheumatism at a documented site that falls outside the joints with their own dedicated codes in the M12.3 subcategory (shoulder, elbow, wrist, hand, hip, knee, ankle/foot). The ICD-10-CM tabular includes a parenthetical note specifically citing vertebral palindromic rheumatism as the prototype use case for this code. Palindromic rheumatism is characterized by recurrent, self-limiting episodes of acute joint inflammation — typically lasting hours to days — followed by complete resolution between attacks, often without residual joint damage in early disease.

Use M12.38 only when the clinician has documented both the diagnosis of palindromic rheumatism AND a specific joint site that doesn't have its own laterality-specific code. If the affected site is one of the standard peripheral joints (shoulder, hip, knee, ankle/foot), drop to the appropriate site-specific code. If multiple joints are involved simultaneously or serially across different sites, consider M12.39 (multiple sites). If the site is genuinely unknown or undocumented, M12.30 (unspecified site) is the fallback.

Palindroming rheumatism can be an early or incomplete presentation of rheumatoid arthritis; rheumatology co-management is common. In the orthopedic setting, M12.38 most frequently surfaces when a patient presents with recurrent spinal or sternoclavicular joint inflammation that doesn't fit a more specific inflammatory arthritis code. Verify that arthrosis (M15–M19) has been ruled out or is separately coded — the M12 category carries an Excludes1 note for arthrosis.

Inclusion & exclusion notes

Per the official ICD-10-CM Tabular List.

Source · CDC ICD-10-CM Official Tabular List · 2026

Includes

Palindromic rheumatism, vertebrae

Sibling codes

Other billable codes under M12.3 (laterality / anatomic variants).

M12.39

Palindromic rheumatism, multiple sites

M12.30

Palindromic rheumatism, unspecified site

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 5 cited references ↓

01What sites are covered by M12.38 versus the other M12.3x codes?

M12.38 covers any specifically documented joint that does not have its own code in M12.3: vertebrae, sternoclavicular, acromioclavicular, temporomandibular, and similar atypical sites. Shoulder (M12.31x), elbow (M12.32x), wrist (M12.33x), hand (M12.34x), hip (M12.35x), knee (M12.36x), and ankle/foot (M12.37x) each have dedicated codes — use M12.38 only when the documented site falls outside that list.

02Is vertebral palindromic rheumatism the only valid use of M12.38?

No. Vertebral involvement is called out in the tabular note as the primary example, but M12.38 applies to any other specifically named site not represented by its own M12.3 subcode — including sternoclavicular, acromioclavicular, or temporomandibular joint involvement.

03When should I use M12.39 instead of M12.38?

Use M12.39 (multiple sites) when the documented encounter describes palindromic rheumatism affecting two or more distinct joint sites, whether simultaneously or as part of a broader flare pattern. M12.38 is reserved for a single, specifically named site that lacks its own code.

04Can M12.38 be coded alongside an osteoarthritis code at the same joint?

No. The M12 category carries an Excludes1 note for arthrosis (M15–M19), meaning these codes cannot be used together for the same joint. If OA and palindromic rheumatism are documented at different sites, each site gets its own appropriate code.

05Does M12.38 require a 7th character?

No. M12.38 is a 5-character billable code under Chapter 13 (M-codes). The 7th-character extension convention (A/D/S) applies to injury S-codes, not to M-codes. M12.38 is complete as-is.

06Is M12.38 accepted by Medicare for chiropractic services?

Yes. CMS's Billing and Coding article for Chiropractic Services (A56273) lists M12.38 explicitly in the Group 3 table of ICD-10-CM codes that support medical necessity, alongside other M12.3x palindromic rheumatism codes.

07What if the site is not documented — can I still use M12.38?

No. 'Other specified site' requires that a specific site be named in the clinical documentation. If the provider documents palindromic rheumatism without identifying the joint, use M12.30 (unspecified site) instead.

Sources & references

Editorial content was developed using the following public sources. Last verified May 8, 2026.

01CDC ICD-10-CM Tabular List 2026 (FY2026, effective Oct 1, 2025)
02
aapc.com
https://www.aapc.com/codes/icd-10-codes/M12.38
03
cms.gov
https://www.cms.gov/medicare-coverage-database/view/article.aspx?articleid=56273&ver=26
04
cms.gov
https://www.cms.gov/icd10m/version37-fullcode-cms/fullcode_cms/P1309.html
05
icd10data.com
https://www.icd10data.com/ICD10CM/Codes/M00-M99/M05-M14/M12-/M12.38

Mira AI Scribe

Mira captures the specific joint site by name, the episodic flare pattern (onset, duration, full resolution between attacks), and any imaging or serologic findings documented at that site. This prevents a fallback to M12.30 (unspecified) or a misroute to a site-specific code that doesn't match the anatomy — both of which can trigger specificity downcodes or payer medical necessity flags.

See how Mira captures M12.38 documentation