Systemic sclerosis and impotence: a clinicopathological correlation.

A hypothesis of the mechanism of systemic sclerosis associated impotence was developed by making a clinicopathological correlation between the results of preoperative erectile function testing and those of pathological examination of excised erectile tissue in an impotent man with systemic sclerosis. Preoperative examination revealed firm corporeal tissue with diminished penile stretch capability. Pharmacocavernosometry/pharmacocavernosography under conditions consistent with trabecular smooth muscle relaxation revealed severe diffuse corporeal veno-occlusive dysfunction. During penile implantation surgery the compact erectile tissue was unable to be dilated and required sharp corporeal tissue excision under direct vision to achieve cylinder insertion. Histological investigation of the excised corporeal tissue demonstrated severe corporeal fibrosis. Computer assisted color histomorphometry revealed that the mean percentage of trabecular smooth muscle area to total erectile tissue area was 18.2 +/- 13.9% (normal 40 to 52). Immunohistochemical staining with desmin, a protein found in smooth muscle, verified prolific corporeal fibrosis. In situ hybridization of the corporeal tissue demonstrated messenger ribonucleic acid collagen and fibronectin messenger ribonucleic acid expression. Strong hybridization signals were found in mesenchymal cell types, including trabecular smooth muscle cells. In summary, clinicopathological correlation revealed that veno-occlusive dysfunction and loss of penile length were secondary to the excessive accumulation of extracellular matrix, partially due to trabecular smooth muscle cells undergoing synthetic as opposed to contractile phenotypic activity.