M85.579

Aneurysmal bone cyst, unspecified ankle and foot

FY2027Chapter 13: Diseases of the musculoskeletal system and connective tissue/M80–M85 Disorders of bone density and structure

BillableComplete code, valid to report

M85.579 (also written M85579) is a billable ICD-10-CM diagnosis code for aneurysmal bone cyst, unspecified ankle and foot. It is part of the FY2027 code set, effective October 1, 2026. It is one of the 169 codes in category M85 (Other disorders of bone density and structure). Its coding notes include 4 Excludes1 entries and 11 Excludes2 entries.

Excludes1

Not coded here. The listed conditions generally should not be reported together.

Inherited from M85 Other disorders of bone density and structure
  • osteogenesis imperfecta (Q78.0)
  • osteopetrosis (Q78.2)
  • osteopoikilosis (Q78.8)
  • polyostotic fibrous dysplasia (Q78.1)

Excludes2

Not included here. Both codes may be reported if the patient has both conditions.

Inherited from M85.5 Aneurysmal bone cyst
  • aneurysmal cyst of jaw (M27.4)
Also from chapter/block level (10 notes)
Inherited from Chapter 13 Diseases of the musculoskeletal system and connective tissue
  • 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)

Notes

Also from chapter/block level (1 note)
Inherited from Chapter 13 Diseases of the musculoskeletal system and connective tissue
  • Use an external cause code following the code for the musculoskeletal condition, if applicable, to identify the cause of the musculoskeletal condition