M63.80 Disorders of muscle in diseases classified elsewhere, unspecified site

Billable ICD-10-CM code, FY2026.

Applies from M63 Disorders of muscle in diseases classified elsewhere

Excludes1 (never code together)

• myopathy in cysticercosis (B69.81)
• myopathy in endocrine diseases (G73.7)
• myopathy in metabolic diseases (G73.7)
• myopathy in sarcoidosis (D86.87)
• myopathy in secondary syphilis (A51.49)
• myopathy in syphilis (late) (A52.78)
• myopathy in toxoplasmosis (B58.82)
• myopathy in tuberculosis (A18.09)

Code first

• underlying disease, such as:
• leprosy (A30.-)
• neoplasm (C49.-, C79.89, D21.-, D48.1-)
• schistosomiasis (B65.-)
• trichinellosis (B75)

MS-DRG index

Defines the logic of DRG(s) 557-558 in MDC 08.

Approximate ICD-9-CM (GEMs)

• 728.9 Unspecified disorder of muscle, ligament, and fascia (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.

Diagnosis Index entries for M63.80

• Leprosy › with muscle disorder
• Schistosomiasis › with muscle disorder
• Trichinellosis, trichiniasis, trichinelliasis, trichinosis › with muscle disorder

Nearby codes

• M63 Disorders of muscle in diseases classified elsewhere
• M63.8 Disorders of muscle in diseases classified elsewhere
• M63.80 Disorders of muscle in diseases classified elsewhere, unspecified site (this code)
• M63.81 Disorders of muscle in diseases classified elsewhere, shoulder
• M63.811 Disorders of muscle in diseases classified elsewhere, right shoulder
• M63.812 Disorders of muscle in diseases classified elsewhere, left shoulder
• M63.819 Disorders of muscle in diseases classified elsewhere, unspecified shoulder
• M63.82 Disorders of muscle in diseases classified elsewhere, upper arm