Myositis Case Study

A 53 yo F with past medical history of diabetes and hypothyroidism presents with:

• 4 month history of weakness
• Fatigue with washing her hair
• Needs help with changing her clothes
• Difficulty climbing stairs
• Dysphagia, weight loss, and low grade fevers

Physical Exam

• 3/5 strength of shoulder abduction, 4/5 strength of hip flexion, 5/5 strength otherwise
• Erythematous rash anterior chest/neck/posterior shoulders (view image), erythematous rash and nodules over MCPs (view image)
• Purplish rash over eyelids (view image)

Diagnostic Workup

• Labs: CK 13,000,  AST 350, ALT 425, Cr 0.34, ESR 35, TSH wnl, ANA pos
• EMG: increased insertional activity with spontaneous fibrillations, c/w myopathic pattern
• Femur MRI: muscle edema of psoas, rectus femoris, and vastus lateralis muscles

Next Steps & Treatment

Prior to referral, other workup can be initiated:

• Lab workup for myositis specific antibodies and myositis associated antibody panel (ENA, extended myositis panel)
• Referral for muscle biopsy (biopsy side contralateral to EMG)
• Assess for pulmonary involvement
  • HRCT of lung
  • PFTs with DLCO
• TTE or ECG, if concern for cardiac involvement
• Evaluation for underlying malignancy
  • Age appropriate screening: mammogram, colonoscopy, pelvic exam/PAP
  • CXR if history of smoking
  • Remember: presence of >1 high-risk feature (i.e., anti-TIF/anti NXP2, >40 yo, dysphagia, cutaneous necrosis) -> consider CT chest/abdomen/pelvis +/- upper/lower endoscopies, in addition to age appropriate screening

Other Considerations

• What if this patient did not have any muscle weakness?
  • Consider clinically amyopathic dermatomyositis (CADM)
  • These patients can still have ILD, mild CK elevations
• What if this patient presented with mechanic’s hands (view image), significant shortness of breath, fevers, and Raynaud’s? 
  • Consider antisynthetase syndrome, a form of inflammatory myositis