Dialysis‐associated systemic fibrosis (nephrogenic fibrosing dermopathy): Study of inflammatory cells and transforming growth factor β1 expression in affected skin

Abstract

Objective Nephrogenic fibrosing dermopathy (NFD) is a newly recognized cutaneous fibrotic disorder occurring in individuals with end‐stage renal disease (ESRD). The aim of the present study was to describe the clinical and histopathologic features of 9 new cases and to characterize the inflammatory cells and expression of transforming growth factor β1 (TGFβ1) in affected skin. Methods Clinical and laboratory assessments, including serology and pulmonary function studies, were performed in 9 patients undergoing long‐term dialysis (8 hemodialysis; 1 peritoneal dialysis) for ESRD of diverse etiologies. Skin, fascia, striated muscles, lungs, and heart were examined by histopathology. Inflammatory cells were characterized by immunophenotyping using specific monoclonal antibodies. TGFβ1 expression was determined by in situ hybridization. Results All patients displayed cutaneous features resembling both systemic sclerosis and diffuse fasciitis, with severe loss of motion and flexion contractures in multiple joints. Six patients displayed woody induration of the muscles of the legs, thighs, and forearms. Five of the 6 patients with lung involvement had a reduced diffusion capacity for carbon monoxide on pulmonary function testing. Marked elevations of the erythrocyte sedimentation rate and/or C‐reactive protein level were found in 6 patients. Antinuclear antibodies were present at low titers in 4 patients. Histopathologic studies indicated that in addition to the dermis, the fibrotic process affected the subcutaneous tissue, fascia, striated muscles, lungs, and myocardium. Large numbers of CD68+/factor XIIIa+ dendritic cells and increased expression of TGFβ1 were found in affected skin and muscle. Conclusion Our findings indicate that the fibrotic process of NFD affects not only the dermis, but also the subcutaneous tissues, fascia, and other organs, including striated muscles, heart, and lungs. We therefore believe this is a systemic fibrosing process, and we suggest that dialysis‐associated systemic fibrosis would be a better term for the condition.