But only about 30,000 have been diagnosed , according to The Myositis Association .
Some 50,000 to 75,000 Americans live with myositis , a broad bucket of inflammatory muscle diseases , including inclusion - body myositis .
Only about 30,000 have been diagnosed , according to The Myositis Association .
Some 50,000 to 75,000 Americans live with myositis , a broad bucket of inflammatory muscle diseases , including inclusion - body myositis .