[An unusual constellation of findings in polymyositis--differential diagnosis and clinical course].

Clinical and biochemical findings are described in a 34-year-old female with atypical polymyositis. Uncommon clinical features in this patient included distally accented decreased muscle strength and myalgias, atypical electromyographic findings, a remarkable discrepancy between clinical findings and laboratory parameters of myolysis, unexplained episodes of somnolism, presence of increased serum lactate levels, and a unilateral mamma aplasia. For this combination of signs a polymyositis or an inclusion body myositis, but also a metabolic or heredodegenerative myopathy was considered. Finally, the idiopathic polymyositis was confirmed histologically and a marked improvement in the clinical and biochemical signs occurred after commencement of high-dose methylprednisolone.