Misdiagnosis of Inclusion Body Myositis: Two Case Reports and a Retrospective Chart Review

Amaiak Chilingaryan; Richard A. Rison; Said R. Beydoun


J Med Case Reports. 2015;9(169) 

In This Article

Abstract and Introduction


Introduction: Sporadic inclusion body myositis is the most common adult myopathy in persons aged 50 years and older. The clinical presentation includes a chronic, slowly progressive course with a predilection for weakness of the forearm flexors and quadriceps muscles. Its indolent course makes it a disease frequently missed or misdiagnosed as other neuromuscular conditions by health care professionals. The degenerative processes with amyloid accumulation distinguish sporadic inclusion body myositis from other inflammatory myopathies. Currently, no effective therapy exists. This clinical report highlights the difficulties in diagnosing the disease, examples of misdiagnosis, and inappropriate therapies that can result from misdiagnosis.

Case presentation: We present our clinical experience with 20 patients over a 10-year period and describe in depth two cases, both men, one of Indian ethnicity and the other of Hispanic ethnicity, who were referred to our neuromuscular division for second opinions and diagnosed with sporadic inclusion body myositis years after symptom onset.

Conclusions: Although sporadic inclusion body myositis is rare and without effective therapy, accurate diagnosis is crucial to providing adequate counseling and information about the prognosis and disease course, and to avoiding inappropriate therapy.


Sporadic inclusion body myositis (s-IBM) is one of several chronic adult inflammatory myopathies. Its prevalence varies, but it may be as high as 35 per 1 million adults over age 50 years, with a slight male predominance.[1] The clinical presentation involves chronic, slowly progressive, distal asymmetric weakness affecting the finger flexors and proximal lower extremity weakness affecting the quadriceps, which later progresses to other proximal and distal muscles. The indolent disease course sometimes lasts many years until patients notice significant deterioration leading to medical care.[2–4] Additional complaints include dysphagia caused by cricothyroid muscle weakness and decreased pharyngeal propulsion.[5] The pathogenesis of s-IBM is not fully understood, and currently there is no known treatment.[3,6] We present two exemplary cases followed by a summary table that highlights the presentation of 20 patients seen in our clinic over a 10-year period.