Collapsing glomerulopathy in a patient with mixed connective tissue disease.

Collapsing glomerulopathy (CG) is a distinct clinicopathological entity characterized by glomerular capillary collapse, podocyte proliferation, diffuse mesangial sclerosis, and podocyte maturation arrest. Initially noted primarily in HIV infected patients, a number of other diseases have now been associated with CG. Mixed connective tissue disease (MCTD) is a disease with overlapping features of systemic lupus erythematosus, progressive systemic sclerosis, and polymyositis. It was originally thought that renal involvement was a rare complication of MCTD. However, over the years, it has become clearer that renal involvement, although not always clinically apparent, is frequent. In this report we present a patient with MCTD who developed CG.