M85.50 — Aneurysmal bone cyst, unspecified site

BillableUnspecified

Is M85.50 billable?

Yes, but M85.50 is an unspecified code. M85.50 is a valid, billable ICD-10-CM code for encounters from October 1, 2026 through September 30, 2027. However, M85.50 is an unspecified or catch-all code. Payers apply additional scrutiny to unspecified codes and many deny them when the medical record supports a more specific option, so check the documentation before selecting M85.50 — the more specific alternatives are listed below.

More specific alternatives

M85.50 at a glance

Code	M85.50
Description	Aneurysmal bone cyst, unspecified site
Billable	Yes
Code set	ICD-10-CM FY2027
Valid for encounters	October 1, 2026 – September 30, 2027

Which MS-DRGs does M85.50 group to?

M85.50 sits in MDC 08 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.

553Bone Diseases and Arthropathies with MCCmedical
554Bone Diseases and Arthropathies without MCCmedical

How is M85.50 listed in the Alphabetic Index?

These are the routes through the Alphabetic Index that lead to M85.50. They show the wording a clinician may have documented, which often differs from the Tabular description.

Cyst › boneNEC › aneurysmal (colloid) (mucous) (simple) (retention)

Excludes1 — never code together — inherited from M85

The conditions below can never be reported together with M85.50 on the same claim. An Excludes1 note means the two conditions cannot occur in the same patient, so reporting both is a coding error.

osteogenesis imperfecta (Q78.0)
osteopetrosis (Q78.2)
osteopoikilosis (Q78.8)
polyostotic fibrous dysplasia (Q78.1)

Excludes2 — not included here — inherited from Chapter 13

The conditions below are not part of M85.50, but a patient may have both at the same time. When documentation supports it, M85.50 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)

Excludes2 — not included here — inherited from M85.5

The conditions below are not part of M85.50, but a patient may have both at the same time. When documentation supports it, M85.50 and the excluded code may both be reported.

aneurysmal cyst of jaw (M27.4)

How long has M85.50 existed?

M85.50 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.