Perifascicular atrophy of muscle fibres is seen in -

Dermatomyositis is a connective-tissue disease related to polymyositis that is characterized by inflammation of the muscles and the skin. It is a systemic disorder that may also affect the joints, the esophagus, the lungs, and, less commonly, the heart. On the muscle biopsy, there are two classic microscopic findings of dermatomyositis. They are : mixed B- & T-cell perivascular inflammatory infiltrate and perifascicular muscle fiber atrophy. It is associated with autoantibodies, especially anti-Jo 1 antibody.