M85.5 – Aneurysmal bone cyst

ICD-10-CM 2027 diagnosis code · Disorders of bone density and structure

Non-billable header

ICD-10-CM code M85.5

Code: M85.5 (claims format: M855)
Description: Aneurysmal bone cyst
Billable: No – use a more specific code below
Valid for: Dates of service October 1, 2026 – September 30, 2027 (FY2027)
Chapter: 13. Diseases of the musculoskeletal system and connective tissue (M00-M99)
Block: M80-M85 Disorders of bone density and structure
Parent codes: M85

Billable codes under M85.5

M85.5 is a header code and cannot be used on claims. Choose the most specific code:

M85.50 – Aneurysmal bone cyst, unspecified siteBillable
M85.51 – Aneurysmal bone cyst, shoulderHeader (more codes below)
M85.52 – Aneurysmal bone cyst, upper armHeader (more codes below)
M85.53 – Aneurysmal bone cyst, forearmHeader (more codes below)
M85.54 – Aneurysmal bone cyst, handHeader (more codes below)
M85.55 – Aneurysmal bone cyst, thighHeader (more codes below)
M85.56 – Aneurysmal bone cyst, lower legHeader (more codes below)
M85.57 – Aneurysmal bone cyst, ankle and footHeader (more codes below)
M85.58 – Aneurysmal bone cyst, other siteBillable
M85.59 – Aneurysmal bone cyst, multiple sitesBillable

Notes for M85.5

Excludes2 (not included here):

aneurysmal cyst of jaw (M27.4)

Notes inherited from parent codes

Instructional notes at a category or block level apply to every code below it.

M85 – Other disorders of bone density and structure

Excludes1 (not coded here):

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

Related codes in M85

M85.0 – Fibrous dysplasia (monostotic)Header
M85.1 – Skeletal fluorosisHeader
M85.2 – Hyperostosis of skullBillable
M85.3 – Osteitis condensansHeader
M85.4 – Solitary bone cystHeader
M85.6 – Other cyst of boneHeader
M85.8 – Other specified disorders of bone density and structureHeader
M85.9 – Disorder of bone density and structure, unspecifiedBillable

Frequently asked questions

What is ICD-10 code M85.5?

M85.5 is the ICD-10-CM code for aneurysmal bone cyst, in the block M80-M85 (Disorders of bone density and structure).

Is M85.5 a billable code?

No. M85.5 is a header code with more specific child codes; report one of the billable codes listed above.

What category does M85.5 belong to?

It belongs to category M85 – Other disorders of bone density and structure.

Source: CDC/NCHS ICD-10-CM FY2027 code files, tabular list and index. Reference only – code assignment must follow the official ICD-10-CM guidelines and documentation in the medical record.