Granulomatous myositis mimicking slowly progressive lower motor neuron disease

Here we illustrate a 74-year-old patient presenting with clinical signs of slowly progressive motor neuron disease. After electromyography demonstrated myopathic changes, a skeletal muscle biopsy was performed showing histological signs of granulomatous myositis. In extensive diagnostic workup underlying primary granulomas forming diseases were excluded and corticoid therapy was initiated, but without clinical effect. We want to point out that granulomatous myositis should be considered in the differential diagnosis of slowly progressive motor neuron diseases, especially in atypical clinical presentations.