M79.4 — Hypertrophy of (infrapatellar) fat pad

Billable

Is M79.4 billable?

Yes — M79.4 is billable for FY2027. M79.4 is a valid, billable ICD-10-CM code at the highest level of specificity in its branch. M79.4 may be submitted for encounters from October 1, 2026 through September 30, 2027.

M79.4 at a glance

Code	M79.4
Description	Hypertrophy of (infrapatellar) fat pad
Billable	Yes
Code set	ICD-10-CM FY2027
Valid for encounters	October 1, 2026 – September 30, 2027

Which MS-DRGs does M79.4 group to?

M79.4 sits in MDC 09 and helps define the logic of 2 MS-DRGs (version 44, FY2027). Which one a stay actually groups to also depends on procedures and secondary diagnoses.

606Minor Skin Disorders with MCCmedical
607Minor Skin Disorders without MCCmedical

How is M79.4 listed in the Alphabetic Index?

These are the routes through the Alphabetic Index that lead to M79.4. They show the wording a clinician may have documented, which often differs from the Tabular description.

Degeneration, degenerative › infrapatellar fat pad
Degeneration, degenerative › popliteal fat pad
Fibrosis, fibrotic › infrapatellar fat pad
Fibrosis, fibrotic › popliteal fat pad
Fat › localized › knee
Fat › localized › retropatellar
Fat › pad › knee
Hypertrophy, hypertrophic › fat pad › knee

Excludes1 — never code together — inherited from M79

The conditions below can never be reported together with M79.4 on the same claim. An Excludes1 note means the two conditions cannot occur in the same patient, so reporting both is a coding error.

psychogenic rheumatism (F45.8)
soft tissue pain, psychogenic (F45.41)

Excludes2 — not included here — inherited from Chapter 13

The conditions below are not part of M79.4, but a patient may have both at the same time. When documentation supports it, M79.4 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)

How long has M79.4 existed?

M79.4 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.