Immune complex vasculitis, polymyositis, and hyperglobulinemic purpura.

This is the first description of a patient with both polymyositis and Waldenström hyperglobulinemic purpura. There was evidence of circulating immune complexes, and immune deposits were found in dermal and muscular vessels. Similar electron-dense deposits were seen ultrastructurally in the basement membrane of both normal and abnormal microvasculature. The findings suggest that the muscle and skin lesions may be associated with deposition of circulating immune complexes in and around blood vessels, followed by complement activation and subsequent inflammation.