Mixed connective tissue disease presenting as a peculiar myositis with poor muscle regeneration

Mixed connective tissue disease (MCTD) is a rheumatological disease which has to be distinguished from other entities causing inflammatory myopathy. The usual clinical presentation of inflammatory myopathy associated with connective tissue disease is not different from isolated polymyositis or dermatomyositis, i.e., subacute onset of proximal weakness affecting both upper and lower girdle with high serum CK level. Here we report a patient with MCTD/myositis overlap syndrome displaying an uncommon clinical presentation and a distribution of muscle weakness involving facial, neck and arm muscles with sparing of lower limbs. We also describe the scarcity of muscle regeneration signs on the muscle biopsy with complete absence of alkaline phosphatase positivity in the endomysial and permysial connective tissue as a novel finding of this condition.