M85.042 Fibrous dysplasia (monostotic), left hand

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

• M85.031 Fibrous dysplasia (monostotic), right forearm
• M85.032 Fibrous dysplasia (monostotic), left forearm
• M85.039 Fibrous dysplasia (monostotic), unspecified forearm
• M85.04 Fibrous dysplasia (monostotic), hand
• M85.041 Fibrous dysplasia (monostotic), right hand
• M85.042 Fibrous dysplasia (monostotic), left hand (this code)
• M85.049 Fibrous dysplasia (monostotic), unspecified hand
• M85.05 Fibrous dysplasia (monostotic), thigh
• M85.051 Fibrous dysplasia (monostotic), right thigh
• M85.052 Fibrous dysplasia (monostotic), left thigh
• M85.059 Fibrous dysplasia (monostotic), unspecified thigh