Take two: Utility of the repeat skeletal muscle biopsy

Area of Science:

• Neurology
• Pathology
• Immunology

Background:

• The clinical utility of repeat muscle biopsy remains incompletely understood.
• Advances in diagnosing immune inflammatory myopathies necessitate re-evaluation of diagnostic tools.

Purpose of the Study:

• To evaluate the clinical relevance and utility of repeat muscle biopsy.
• To identify factors influencing the diagnostic yield of repeat muscle biopsies.

Main Methods:

• Retrospective review of 144 repeat muscle biopsies conducted between 1980 and 2017.
• Clinical relevance defined by new diagnosis, diagnostic change, or treatment alteration.

Main Results:

• Repeat biopsies were abnormal in 118 cases and different from initial biopsies in 67 cases.
• Factors like initial biopsy findings (abnormal, specific, inflammatory), proximal muscle weakness, and absence of myalgia significantly impacted relevance.
• Repeat biopsy specificity was noted in 40 cases, with specific diagnoses including polymyositis and inclusion body myositis.

Conclusions:

• The utility of repeat muscle biopsy is restricted, particularly for patients with initial inflammatory myositis and proximal weakness.
• Evolving diagnostic capabilities for immune inflammatory myopathies are reshaping the role of repeat muscle biopsy.