Polymyositis complicating pregnancy.

Reports of dermatomyositis and polymyositis during pregnancy are rare, there being only one previously published case that we know of in the literature. We report a case in which severe polymyositis developed during pregnancy and the patient experienced dramatic improvement following delivery. Since there is evidence that polymyositis is an immune-mediated disease, one has to speculate that the fetus and its complement of foreign antigens might have played a role in the patient's disease.