Severe damage of respiratory muscles in polymyositis

Objectives – to present a clinical case of polymyositis in a 55-year-old man. The patient was admitted with a diagnosis "transient ischemic attack", quickly followed by an acute respiratory failure, which required the continuous use of mechanical ventilation. Other clinical symptoms included: a high diaphragm position up to the 4-th ribs, the concurrent purulent endobronchitis, bilateral pneumonia, pleurisy, multiple atelectasis, myocardial dysfunction with a decrease in ejection fraction to 46%, local hypokinesia according to EchoCG data. Despite the severe condition of the patient, there was not registered any distinct impairment of the proximal limb muscles and an increase in creatinphosphokinase blood level. The antinuclear myositis-specific antibodies, the signs of primary muscular damage according to the limb muscles ENMG data were also absent. The paraneoplastic process was excluded. The results of clinical examination made the diagnosis of polymyositis uncertain. To clarify the cause of the respiratory muscles damage, an intercostal muscle biopsy was performed.It revealed expressed changes in the muscle, with massive necrosis areas, and perivascular lymphohistiocytic infiltration.

Conclusion. The described case of polymyositis is extremely rare, has a severe course and is complicated for diagnosis and treatment. In this case, the most informative examination method can be a biopsy of the intercostal muscles, which allows to identify the inflammatory origine of the disease and to determine the pathogenetic therapy.