M90.661 Osteitis deformans in neoplastic diseases, right lower leg

Billable ICD-10-CM code, FY2026.

Applies from M90 Osteopathies in diseases classified elsewhere

Excludes1 (never code together)

• osteochondritis, osteomyelitis, and osteopathy (in):
• cryptococcosis (B45.3)
• diabetes mellitus (E08-E13 with .69-)
• gonococcal (A54.43)
• neurogenic syphilis (A52.11)
• renal osteodystrophy (N25.0)
• salmonellosis (A02.24)
• secondary syphilis (A51.46)
• syphilis (late) (A52.77)

Applies from M90.6 Osteitis deformans in neoplastic diseases

Applicable to

• Osteitis deformans in malignant neoplasm of bone

Excludes1 (never code together)

• osteitis deformans [Paget's disease of bone] (M88.-)

Code first

• the neoplasm (C40.-, C41.-)

MS-DRG index

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

Approximate ICD-9-CM (GEMs)

• 731.1 Osteitis deformans in diseases classified elsewhere (approximate)

Medicare Code Edits (MCE v43.1 (April 2026))

• Manifestation codes as principal diagnosis: Manifestation codes describe the manifestation of an underlying disease, not the disease itself, and are not allowed as principal diagnosis.

Code annotations containing back-references to M90.661

Back-references to M90.6

• Type 1 Excludes: M88 Osteitis deformans [Paget's disease of bone] ("osteitis deformans in neoplastic disease (M90.6)")

Back-references to M90

• Type 1 Excludes: M87 Osteonecrosis ("osteochondropathies (M90-M93)")

Nearby codes

• M90.65 Osteitis deformans in neoplastic diseases, thigh
• M90.651 Osteitis deformans in neoplastic diseases, right thigh
• M90.652 Osteitis deformans in neoplastic diseases, left thigh
• M90.659 Osteitis deformans in neoplastic diseases, unspecified thigh
• M90.66 Osteitis deformans in neoplastic diseases, lower leg
• M90.661 Osteitis deformans in neoplastic diseases, right lower leg (this code)
• M90.662 Osteitis deformans in neoplastic diseases, left lower leg
• M90.669 Osteitis deformans in neoplastic diseases, unspecified lower leg
• M90.67 Osteitis deformans in neoplastic diseases, ankle and foot
• M90.671 Osteitis deformans in neoplastic diseases, right ankle and foot
• M90.672 Osteitis deformans in neoplastic diseases, left ankle and foot