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v1.0.0
ICD-10 Guide
DiagnosesPolymyositis

Polymyositis

ICD-10 Coding for Polymyositis(M33.22, M33.21, M33.29)

PRIMARY SPECIALTYRheumatology
COMPLEXITYHigh
LAST UPDATED09/15/2025
Sam Tuffun, PT, DPT
Physical Therapist | Medical Coding & Billing Contributor

Diagnosis Overview

What is Polymyositis?
Essential facts and insights about Polymyositis

Key Clinical Considerations:

  • Symmetrical proximal muscle weakness
  • Elevated muscle enzymes (e.g., CK, aldolase)
  • Muscle biopsy showing inflammatory infiltrates

Clinical Information

Clinical Criteria & Documentation Requirements

  • Patient history of muscle weakness and fatigue
  • Results of laboratory tests and imaging studies
  • Detailed description of physical examination findings

Coding Guidelines

Usage Guidelines & Examples

  • Follow guidelines for specificity in coding polymyositis versus other myopathies.
  • Common errors include misclassifying polymyositis as dermatomyositis.

Code Exclusions

Important Exclusions

  • Excludes conditions like dermatomyositis and inclusion body myositis
  • Alternative codes for myopathy due to other causes

Related ICD-10 Codes

Primary Codes
M33.1
Polymyositis
Ancillary Codes
R94.6
J84.9
Differential Codes
G72.41
D86.0
M33.1

Related CPT Codes

CPT codes will be available in a future update.

Specialty Focus

Primary Specialty

Rheumatology

Specialty Applications

  • Adults aged 30-60, particularly women
  • Rheumatology clinics and outpatient settings

Coding Complexity

High Complexity

This diagnosis requires careful attention to:

  • Comprehensive clinical documentation
  • Accurate code selection based on clinical criteria
  • Proper exclusion considerations
  • Specialty-specific coding guidelines

Documentation

Documentation Templates

Billing Information

Billing Considerations

  • Ensure proper documentation for billing
  • Verify code specificity requirements
  • Check for any additional codes needed
  • Review payer-specific guidelines

Common Issues

  • Insufficient clinical documentation
  • Incorrect code selection
  • Missing supporting diagnoses
  • Timing and frequency documentation

Frequently Asked Questions

What are the documentation requirements?

Document muscle weakness, lab results, and treatment response.

What are the billing considerations?

Ensure accurate coding to reflect severity and associated conditions.