M12.26 — Villonodular synovitis (pigmented), knee

Not billable

Is M12.26 billable?

No — M12.26 is a non-billable header code. M12.26 groups more specific codes and cannot be submitted on a claim. A valid ICD-10-CM code must be reported at the highest level of specificity available in its branch. Select one of the 3 billable codes beneath M12.26.

Billable codes under this header

M12.26 at a glance

Code	M12.26
Description	Villonodular synovitis (pigmented), knee
Billable	No — header code
Code set	ICD-10-CM FY2027
Valid for encounters	October 1, 2026 – September 30, 2027

How is M12.26 listed in the Alphabetic Index?

These are the routes through the Alphabetic Index that lead to M12.26. They show the wording a clinician may have documented, which often differs from the Tabular description.

Synovitis › villonodular › knee

Excludes1 — never code together — inherited from M12

The conditions below can never be reported together with M12.26 on the same claim. An Excludes1 note means the two conditions cannot occur in the same patient, so reporting both is a coding error.

arthrosis (M15-M19)
cricoarytenoid arthropathy (J38.7)

Excludes2 — not included here — inherited from Chapter 13

The conditions below are not part of M12.26, but a patient may have both at the same time. When documentation supports it, M12.26 and the excluded code may both be reported.

arthropathic psoriasis (L40.5-)
certain conditions originating in the perinatal period (P04-P96)
certain infectious and parasitic diseases (A00-B99)
compartment syndrome (traumatic) (T79.A-)
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)
symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)

What codes fall under M12.26? (3)

How long has M12.26 existed?

M12.26 has been in ICD-10-CM since at least FY2016, the earliest fiscal year on record here.

Derived from the official order files for FY2016–FY2026. FY2017 and FY2020 publish no order file, so those years are not covered.

Which conditions are coded to M12.26?

ICD-10 code for Synovitis