Muscle biopsy practices in the evaluation of idiopathic inflammatory myopathies: An international survey of expert clinicians.

BACKGROUND

Muscle biopsy is an important test in the evaluation of individuals with suspected myopathy, including those with suspected idiopathic inflammatory myopathy (IIM). Various approaches, including open surgical biopsy, needle biopsy and conchotome forceps, have been reported. However the real-world utilisation of these approaches remains unclear. There are no established guidelines for the use of muscle biopsy, or selection of biopsy technique, in investigating IIM and international practices are not well-documented. This study describes current approaches to muscle biopsy amongst clinicians with expertise in IIM.

METHODS

A survey regarding muscle biopsy practices was disseminated among members of the International Myositis Assessment and Clinical Studies (IMACS) group. Data were analysed using descriptive statistics.

RESULTS

One-hundred and sixteen clinicians completed the survey, primarily rheumatologists. Open surgical biopsy was the most commonly employed technique (74.5 %), followed by needle (11.3 %) and conchotome (9.4 %) approaches. Clinical examination was the most common method of muscle selection, with 85.2 % of respondents reporting they 'always or almost always' relied on it. MRI and electromyography were also frequently utilised for muscle selection (51.9 %, 45.4 % respectively). There was variability in the perceived utility of muscle biopsy in certain clinical contexts, such as presence of myositis specific antibodies or cutaneous manifestations of dermatomyositis. While respondents generally reported low complication rates following muscle biopsy, non-diagnostic histopathology was commonly reported, regardless of procedural approach.

CONCLUSION

Clinicians managing IIM report muscle biopsy to be well tolerated however, non-diagnostic results are common. Substantial heterogeneity regarding perceived indications for biopsy, procedural approaches, and muscle selection strategies were observed within this expert group. Future research is needed to establish best practice and determine the role of muscle biopsy in the context of continued advancements in serological profiling of IIM.