Sarcoid myopathy and mitochondrial respiratory chain defects: clinicopathological, biochemical and molecular biological analyses.
We report on a 33-yr-old female patient with myalgia, CK values up to 3500 Ul-1 and proximal weakness. An initial muscle biopsy showed myositis. One year later an enlarged lymph node was investigated and sarcoidosis diagnosed. In a second muscle biopsy inflammatory cells and morphological characteristics of mitochondrial myopathy were found. Biochemical analyses indicated a 50% reduction in complex II activity of the respiratory chain. Due to failure in clinical improvement a third muscle biopsy was performed in 1990 where only 19% of normal complex II activity was present. Southern blot analysis of the mitochondrial genome was normal. Thus for the first time we describe a patient with sarcoid myopathy and a complex II deficiency. Our interpretation is that a pre-existing complex II defect became clinically relevant because of additional sarcoid myopathy.