M85.40 Solitary bone cyst, unspecified site

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 M85.4 Solitary bone cyst

Excludes2 (not included here)

• solitary cyst of jaw (M27.4)

MS-DRG index

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

Approximate ICD-9-CM (GEMs)

• 733.21 Solitary bone cyst (approximate)

Diagnosis Index entries for M85.40

• Cyst (colloid) (mucous) (simple) (retention) › bone (local) NEC › solitary

Nearby codes

• M85.372 Osteitis condensans, left ankle and foot
• M85.379 Osteitis condensans, unspecified ankle and foot
• M85.38 Osteitis condensans, other site
• M85.39 Osteitis condensans, multiple sites
• M85.4 Solitary bone cyst
• M85.40 Solitary bone cyst, unspecified site (this code)
• M85.41 Solitary bone cyst, shoulder
• M85.411 Solitary bone cyst, right shoulder
• M85.412 Solitary bone cyst, left shoulder
• M85.419 Solitary bone cyst, unspecified shoulder
• M85.42 Solitary bone cyst, humerus