M85.079 Fibrous dysplasia (monostotic), unspecified ankle and foot

Billable ICD-10-CM code, FY2026.

Applies from M85 Other disorders of bone density and structure

Excludes1 (never code together)

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

Applies from M85.0 Fibrous dysplasia (monostotic)

Excludes2 (not included here)

• fibrous dysplasia of jaw (M27.8)

MS-DRG index

Defines the logic of DRG(s) 553-554 in MDC 08.

Approximate ICD-9-CM (GEMs)

• 733.29 Other bone cyst (approximate)

Nearby codes

• M85.062 Fibrous dysplasia (monostotic), left lower leg
• M85.069 Fibrous dysplasia (monostotic), unspecified lower leg
• M85.07 Fibrous dysplasia (monostotic), ankle and foot
• M85.071 Fibrous dysplasia (monostotic), right ankle and foot
• M85.072 Fibrous dysplasia (monostotic), left ankle and foot
• M85.079 Fibrous dysplasia (monostotic), unspecified ankle and foot (this code)
• M85.08 Fibrous dysplasia (monostotic), other site
• M85.09 Fibrous dysplasia (monostotic), multiple sites
• M85.1 Skeletal fluorosis
• M85.10 Skeletal fluorosis, unspecified site
• M85.11 Skeletal fluorosis, shoulder