26th February 2025

Inclusion-body myositis

This is a rarer form of inflammatory myositis, accounting for around 20% of cases. It is more common in middle-aged men. Compared to PM or DM as it presents with more predominant distal weakness, such as reduced grip strength, along with proximal muscle weakness. Dysphagia is also commonly seen, although dysarthria is not. An open biopsy is required for diagnosis.

Patients are not generally steroid responsive; however, these are usually given as initial treatment with subsequent DMARD therapy, such as methotrexate.