Ultrastructural evidence of dermal gadolinium deposits in a patient with nephrogenic systemic fibrosis and end-stage renal disease.

The pathogenesis of acquired nephrogenic systemic fibrosis recently described for patients with renal insufficiency and a history of exposition to gadolinium-based magnetic resonance contrast agents is not completely understood. A role for circulating fibroblasts in the fibrosing tissue is hypothetical, and the mechanism of the assumed trigger function of gadolinium remains elusive. A skin lesion on a 76-yr-old man with symptoms of nephrogenic systemic fibrosis lasting 5 mo was studied at the ultrastructural level. After confirmation of he diagnosis by histopathologic methods, the presence and distribution of gadolinium, iron, calcium, and magnesium by energy filtering transmission electron microscopy was also examined. The performed electron spectroscopic imaging and electron energy loss spectroscopic analyses on deparaffinized samples revealed deposition of gadolinium in irregular small aggregates that adhered to cell profiles and collagen fibers of the connective tissue, forming a perivascular "gadolinium-deposit zone" in the skin. Traces of iron signal were demonstrated in singular gadolinium-positive deposits, and iron presence was found in adjacent connective tissue. The ultrastructural cell analysis of the lesion showed among numerous poorly differentiated fibrocytes also higher differentiated cells with myofibroblastic characteristics, including bundles of intermediate filaments and attachment plaques in the cell periphery, indicating an ability of lesional fibroblasts to differentiate into myofibroblastic cells. These findings support the pivotal role of gadolinium chelates in the development of nephrogenic systemic fibrosis.