Ultrasound Guided Open Muscle Biopsy (P2.464)

Objective: Determine if muscle ultrasound (MUS) guided open muscle biopsies improve the histologic diagnostic viability in patients with suspected myositis Background: In approximately 10–20% of patients with clinically active disease, muscle biopsies can be negative due to sampling error. Muscle imaging, such as MUS, may be a cost-effect adjunct in selecting potential pathological areas thus reducing false negative findings on histopathology. Design/Methods: Four patients with proximal muscle weakness and muscle atrophy underwent MUS prior to open muscle biopsy. Muscles were chosen based on their increased echogenicity and accessibility. Areas with increased echogenicity and attenuation typically seen in fibrosis were avoided. The specific location for biopsy was marked. Open muscle biopsy was performed and a 5 mm × 5 mm piece of muscle was extracted. Muscle biopsies were prepared for histological evaluation via standard practices. Results: All 4 cases demonstrated variation in myofiber size and configuration with numerous foci of inflammation and evidence of degenerating/regenerating myofibers consistent with myositis. The resultant diagnoses included inclusion body myositis, dermatomyositis, necrotizing myopathy, and polymyositis. Conclusions: MUS is cost effective test prior to open muscle biopsy improving diagnostic accuracy in myositis. Disclosure: Dr. Sultan has nothing to disclose. Dr. Gyure has nothing to disclose. Dr. Smith has nothing to disclose.