Nephrogenic systemic fibrosis: A clinicopathologic study of six cases

A Systematic Review of 639 Patients with Biopsy-confirmed Nephrogenic Systemic Fibrosis

Background Although nephrogenic systemic fibrosis (NSF) affects the use of gadolinium-based contrast agents (GBCAs) in MRI, there continues to be limited knowledge because of the small number of patients with NSF. Purpose To perform a systematic review of NSF. Materials and Methods PubMed database was searched by using the term "Nephrogenic systemic fibrosis" from January 2000 to February 2019. Articles reporting details on individual patients with NSF diagnosis on the basis of both clinical presentations and biopsy confirmation were included. Data were pooled and authors were contacted for clarifications. Rates of NSF were compared through 2008 versus after 2008 and for group I versus group II GBCAs, assuming equal market share. Results Included were 639 patients from 173 articles. Data regarding sex were found for 295 men and 254 women. Age at NSF symptom onset was reported for 177 patients (mean, 49 years ± 16 [standard deviation]; age range, 6-87 years). There were 529 patients with documented exposure to GBCAs including gadodiamide (n = 307), gadopentetate dimeglumine (n = 49), gadoversetamide (n = 6), gadobutrol (n = 1), gadobenate dimeglumine (n = 1), multiple (n = 41), and unknown (n = 120). Among patients with previous exposure, only seven patients were administered GBCA after 2008, yielding a lower rate of NSF after 2008 (P < .001). There were motion limitations in 70.8% (296 of 418) of patients, indicating a more serious debilitation. Associated factors reported for NSF included exposure to GBCA group I (P < .001), dialysis, proinflammatory conditions, hyperphosphatemia, β-blockers, and epoetin. For 341 patients with follow-up, 12 patients were cured and 72 patients partially improved including one during pregnancy. Among those 84 patients reported as cured or improved, in 34 patients cure or improvement occurred after renal function restoration. Four deaths were attributed to NSF. Conclusion Although 639 patients with biopsy-confirmed nephrogenic systemic fibrosis were reported, only seven were after gadolinium-based contrast agent exposure after 2008, indicating that regulatory actions and practice changes have been effective preventive measures. Improvement and sometimes cure with renal function restoration are now possible. © RSNA, 2019 See also the editorial by Davenport in this issue.

Pathophysiology of gadolinium-associated systemic fibrosis

Systemic fibrosis from gadolinium-based magnetic resonance imaging contrast is a scourge for the afflicted. Although gadolinium-associated systemic fibrosis is a rare condition, the threat of litigation has vastly altered clinical practice. Most theories concerning the etiology of the fibrosis are grounded in case reports rather than experiment. This has led to the widely accepted conjecture that the relative affinity of certain contrast agents for the gadolinium ion inversely correlates with the risk of succumbing to the disease. How gadolinium-containing contrast agents trigger widespread and site-specific systemic fibrosis and how chronicity is maintained are largely unknown. This review highlights experimentally-derived information from our laboratory and others that pertain to our understanding of the pathophysiology of gadolinium-associated systemic fibrosis.

Immunohistochemical aspects of the fibrogenic pathway in nephrogenic systemic fibrosis

Nephrogenic systemic fibrosis (NSF) is a rare gadolinium-dependent disorder of the skin and viscera. The aim of this study was to revisit some immunopathologic clues of NSF, including the characterization of glycosaminoglycans, cell tensegrity, and cell proliferation in the dermis. Immunohistochemistry was done using antibodies directed to vimentin, CD34, Factor XIIIa, calprotectin, α-smooth muscle actin, Ulex europaeus agglutinin-1 (UEA-1), and MIB1/Ki67 and to glycosaminoglycans, including CD44 var3, versican, and perlecan. The vimentin+ cell density was markedly increased. The vast majority of them corresponded to CD34+ or Factor XIIIa+ dermal dendrocytes (DD) showing distinct cell tensegrity. CD34+DD were slender, elongated, and usually scattered in the dermis but focally clustered in nodular collections. By contrast, Factor XIIIa+ was plump with squat dendrites showing no evidence for being under mechanical stress. Cells in the vicinity of the microvasculature were rounded and exhibited calprotectin immunoreactivity typical for monocyte/macrophages. The microvasculature highlighted by UEA-1 and α-smooth muscle actin looked unremarkable. The cell proliferation highlighted by the MIB/Ki67 immunoreactivity was unusually high (>20%) in the interstitial stromal cells. Stromal cells enriched in versican were plump, abundant, and seemed interconnected each other by a dense network of dendrites. By contrast, the immunolabeling for perlecan and CD44 var 3 was unremarkable. In conclusion, the cell population involved in NSF seemed phenotypically heterogeneous, and its growth fraction was clearly boosted in the skin. The intracellular load in versican was prominent. The aspect of cell tensegrity did not suggest the influence of mechanical stress putting stromal cells under tension in the dermis.

Imaging patients with kidney disease: how do we approach contrast-related toxicity?

The approach to imaging patients with kidney disease with iodinated radiocontrast and gadolinium-based contrast has changed dramatically in recent times. The complications of these contrast agents, radiocontrast nephropathy and nephrogenic systemic fibrosis, respectively, underlie the changes in the imaging practice used in these patients. Rather than to completely avoid the use of these contrast agents, one must remain judicious in the choice of imaging modality in this group of patients. A prudent approach would be to (1) identify patients at high risk to develop contrast-related complications, (2) use noncontrast-based imaging techniques in these patients, as long as they are suitably diagnostic and safe and (3) if the risk:benefit ratio of the imaging information favors a contrast-based study, then appropriate prophylactic steps and use of contrast agents with the lowest risk of complication should be used after obtaining informed consent. This will allow one to maximize the diagnostic efficiency while also limiting the adverse effects.

MRI safety: nephrogenic systemic fibrosis and other risks

Magnetic resonance imaging (MRI) is now a commonly used imaging modality in many neurosurgical and neurological conditions. Although generally regarded as safe, there are a number of important safety considerations. These include a recently recognised, rare condition termed nephrogenic systemic fibrosis (NSF) that occurs in patients with significant renal impairment who receive gadolinium based contrast. Currently, NSF remains poorly understood and there is no universally effective treatment beyond the avoidance of contrast in patients with significant renal impairment. Other safety considerations include MRI contraindicated devices and the role of MRI in pregnancy.

The outcome of patients with nephrogenic systemic fibrosis after successful kidney transplantation

Nephrogenic systemic fibrosis (NSF) is a debilitating disease in patients with severely diminished kidney function. Currently, no standard treatment exists but improvement has been reported after restoration of kidney function. We retrospectively studied 17 NSF patients with and without successful kidney transplantation (KTx) to evaluate the effects of KTx on NSF. Nine of the 11 KTx developed NSF pretransplant whereas two developed NSF immediately after KTx with delayed graft function. Two of the six dialysis patients had previous failed kidney transplants. Age and sex were well matched. All but one patient was dialysis dependent at the time of NSF. Median follow-up was 35 months for KTx patients and 9 months for dialysis patients. Kidney transplants achieved adequate renal function with median serum creatinine of 1.4 (0.9-2.8) mg/dL and a glomerular filtration rate of 42 (19-60) mL/min/1.73 m(2). NSF improved in 54.6% of the transplanted patients and 50% of the nontransplanted patients (p = 0.86). Two KTx patients had complete resolution of their symptoms whereas four had partial improvement. Improvement in the dialysis patients was all partial. Successful KTx did not insure improvement in NSF and in fact appeared to have no significant benefit over dialysis.

Risk factors for NSF: a literature review

Emerging evidence linking gadolinium-based contrast agents (GBCAs) to nephrogenic systemic fibrosis (NSF) has changed medical practice patterns toward forgoing GBCA-enhanced magnetic resonance imaging (MRI) or substituting other imaging methods, which are potentially less accurate and often radiation-based. This shift has been based on reports of high NSF incidence at sites where a confluence of risk factors occurred in patients with severe renal dysfunction. This review article explores the factors that affect NSF risk, compares risks of alternative imaging procedures, and demonstrates how risk can be managed by careful selection of GBCA dose, timing of injection with respect to dialysis, and other factors. Nearly half of NSF cases are a milder form that does not cause contractures or reduce mobility. It appears that eliminating even a single risk factor can reduce NSF incidence/risk at least 10-fold. Elimination of multiple risk factors by using single-dose GBCA, dialyzing dialysis patients quickly following GBCA administration, avoiding GBCA in acute renal failure while serum creatinine is rising, and avoiding nonionic linear GBCA in renal failure patients may reduce NSF risk more than a thousand-fold, thereby allowing safe GBCA-enhanced MRI in virtually all patients. J. Magn. Reson. Imaging 2009;30:1298-1308. (c) 2009 Wiley-Liss, Inc.

Nephrogenic systemic fibrosis in liver disease: a systematic review

Nephrogenic systemic fibrosis (NSF) may develop in patients with liver disease, a fact highlighted by Food and Drug Administration (FDA) announcements cautioning against the use of gadolinium-based contrast agents (GBCAs) in select liver disease patients. The purpose of this systematic literature review is to characterize the risk of NSF in patients with liver disease. All published articles on NSF from September 2000 through August 2008, were identified via PubMed searches and examination of articles' reference lists. Two reviewers independently read each article and identified unique patients with biopsy-proven or suspected NSF. Data on demographics, liver status, renal status, and GBCA exposure were collected. A total of 324 articles were reviewed, with 108 articles containing case descriptions of 335 unique NSF patients. After excluding the 95/335 (28%) patients in whom the presence or absence of liver disease was uncertain, liver disease was confirmed present in 41/239 (17%) patients. Renal insufficiency could be assessed in 35 of the liver disease patients; severe renal insufficiency, defined as a glomerular filtration rate (GFR) or estimated GFR (eGFR) <30 mL/min/1.73 m(2) or dialysis requirement, was present in 34/35 (97%) patients. The lone patient who developed NSF with mild/moderate renal insufficiency was atypical and received a total gadodiamide load of 0.76 mmol/kg over a 10-week period periliver transplantation. The published medical literature demonstrates that patients with liver disease who develop NSF also have severe renal insufficiency, suggesting that liver disease does not confer a risk for NSF beyond that of the underlying renal insufficiency. J. Magn. Reson. Imaging 2009;30:1313-1322. (c) 2009 Wiley-Liss, Inc.

Advanced kidney disease, gadolinium and nephrogenic systemic fibrosis: the perfect storm

PURPOSE OF REVIEW

Studies of a rare systemic fibrosing condition-entitled nephrogenic systemic fibrosis (NSF) are linked to gadolinium-based contrast (GBC) agent exposure in patients with advanced kidney disease. However, many patients with kidney disease are exposed to GBC agents, yet they do not develop this devastating disorder.

RECENT FINDINGS

NSF appears more likely to develop when the combination of advanced kidney disease, linear GBC agent exposure, and the presence of unique patient features converge. Linear GBC agents are more likely to promote NSF, probably due to chelate-Gd binding instability +/- underlying proinflammatory effects. Patients with advanced acute or chronic kidney disease (CKD) are at highest risk, in contrast to those with lower stages of CKD (stages I-III). Finally, whereas exposure to GBC agents in patients with advanced kidney disease is required for NSF to develop, it does not appear sufficient. Additional patient-specific co-factors, such as metabolic disorders, vascular injury, and inflammation, may also be necessary for NSF to occur.

SUMMARY

NSF develops when 'the perfect storm' of factors is present: unstable/pro-inflammatory GBC agent exposure, advanced kidney disease, and unique patient factors. Recognizing this combination of factors will hopefully allow this devastating condition to become of historical interest only.

Gadolinium-enhanced magnetic resonance imaging for renovascular disease and nephrogenic systemic fibrosis: critical review of the literature and UK experience

PURPOSE

To examine the positive reporting bias regarding the link with gadolinium (Gd) exposure and nephrogenic systemic fibrosis (NSF) in patients with renal impairment. This link has impacted strongly the international radiology safety guidelines. We believe that positive reporting bias has prevailed in the literature and that very few patients with a glomerular filtration rate (GFR) 15-29 mL/min (stage 4 chronic kidney disease [CKD]) should be regarded as high risk.

MATERIALS AND METHODS

To examine this, we conducted the following steps: 1. A critical literature search on NSF. 2. An analysis of our centers magnetic resonance angiography (MRA) experience since 1999. 3. A survey of participating centers of the multicenter ASTRAL trial to assess whether any patients screened or enrolled into ASTRAL had developed NSF.

RESULTS

The vast majority (90%) of NSF cases reported in the literature have occurred in patients with endstage renal disease treated with dialysis; very have had stable stage 4 or 5 (nondialysis) CKD. In all, 562 patients were followed up at our center: 30.4% were CKD4, 14.4% CKD5, 5.3% on dialysis, and 0.2% had renal transplants when imaged. No patients developed any symptoms or signs of NSF. In all, 347 patients were enrolled into ASTRAL on the basis of MRA (32% CKD4/5). One patient out of 45 centers (CKD5, received two Gd scans) developed NSF. Approximately 5 times as many patients were screened as were entered into ASTRAL.

CONCLUSION

No cases of NSF were observed at our center. By extrapolation, 1/1735 patients screened for the ASTRAL trial developed NSF, giving a crude incidence rate of 0.06%. We would argue that patients with CKD4 can safely undergo Gd-MRA, albeit using a minimal dose of a macrocyclic agent and avoiding repeat doses.

MRI safety update 2008: part 1, MRI contrast agents and nephrogenic systemic fibrosis

OBJECTIVE

This article is the first part of a two-part series on MRI safety. In this article, part 1, the topic of MRI contrast agents and nephrogenic systemic fibrosis (NSF) is addressed.

CONCLUSION

To prevent incidents and accidents associated with MRI, it is necessary to regularly revisit the safety topics that directly impact patient management especially with respect to the subjects that are "new" (e.g., MRI contrast agents and NSF), those that should be reassessed because of recent changes, topics that deserve emphasis because of controversy or confusion, and information that should be considered in light of new findings.

Incidence of nephrogenic systemic fibrosis at two large medical centers

PURPOSE

To determine the incidence and associated risk factors of nephrogenic systemic fibrosis (NSF) in patients who undergo gadolinium-based contrast agent (GBCA)-enhanced magnetic resonance (MR) imaging.

MATERIALS AND METHODS

Institutional review board approval was obtained for retrospective review of the medical records from two hospitals to identify all cases of biopsy-confirmed NSF and all patients administered a GBCA from January 1, 1997, to June 30, 2007. Informed patient consent was not required. The incidence of NSF was calculated for patients who received a standard dose of GBCA, patients who received a high dose, and subgroups of patients with renal impairment.

RESULTS

Fifteen patients developed NSF after gadolinium-enhanced MR imaging. All of them had an estimated glomerular filtration rate (eGFR) lower than 30 mL/min, and 11 had acute renal failure or acute deterioration of chronic renal failure. The incidence of NSF after gadolinium-enhanced MR imaging without screening for renal function was zero of 74,124 patients with the standard dose of GBCA and 15 (0.17%) of 8997 patients with the high dose (P < .001). The NSF incidence associated with a high dose of GBCA increased to 0.4% in patients in a chronic hemodialysis program and to 8.8% in those who had an eGFR lower than 15 mL/min but were not undergoing hemodialysis (P < .001). The NSF incidence in the patients with acute renal failure who received a high dose when their creatinine level was increasing was 19% (11 of 58 patients) when hemodialysis was delayed for longer than 2 days. More patients with NSF had proinflammatory events, and compared with patients without NSF, these patients had lower pH, younger age, lower eGFR, elevated serum phosphorus levels, and a longer delay between GBCA injection and hemodialysis.

CONCLUSION

For patients with an eGFR lower than 15 mL/min, hemodialysis helped to prevent NSF. For patients with an eGFR lower than 30 mL/min who received a high dose of GBCA, acute renal failure, delayed hemodialysis after contrast agent injection, proinflammatory events, and hyperphosphatemia were associated with increased risk of NSF.

Nephrogenic systemic fibrosis is associated with transforming growth factor beta and Smad without evidence of renin-angiotensin system involvement

BACKGROUND

The mechanisms of fibrosis associated with nephrogenic systemic fibrosis (NSF) are largely unknown. Transforming growth factor beta (TGF-beta), a known profibrotic cytokine, is theorized to play a central role. The renin-angiotensin system has been linked with both TGF-beta expression and fibrosis in other organ systems.

OBJECTIVE

We sought to investigate whether these mechanisms were involved with NSF.

METHOD

Eleven biopsy specimens from 8 patients with NSF were evaluated by immunohistochemistry for the expression of TGF-beta, Smad 2/3, angiotensin-converting enzyme (ACE), and angiotensin II receptor 1 (AT1).

RESULTS

TGF-beta was detected in 8 of 11 samples of NSF. Smad 2/3 nuclear staining was seen in 8 of 11 samples. Conversely, only faint staining for ACE was seen in 2 of the 11 specimens. No AT1 staining was seen.

LIMITATIONS

We did not perform our studies on a cohort of comparable patients with renal dysfunction without NSF. Our technique may not have been sufficiently sensitive to detect renin-angiotensin system involvement.

CONCLUSIONS

TGF-beta, as well as its second messengers, Smad 2/3, appears to be associated with the fibrosis seen in NSF. No definitive evidence of renin-angiotensin system involvement could be determined.

Nephrogenic systemic fibrosis: possible association with a predisposing infection

OBJECTIVE

Infection at time of MR contrast administration has been reported to predispose patients with renal failure to development of nephrogenic systemic fibrosis (NSF). We assessed the frequency of infection at the time of MR contrast administration in a group of NSF patients.

MATERIALS AND METHODS

Eight patients developed NSF during 2002-2006, of whom seven received the MR contrast agent gadodiamide (Omniscan), with doses of 0.10-0.31 mmol/kg. Data for the following were available for only 2005 and 2006: numbers of infected and uninfected renal failure patients who received MR contrast material and number of contrast-enhanced MR scans in all patients. We extrapolated data to 2002-2006 to approximate rates of NSF in infected and uninfected renal failure patients using Fisher's exact test for association between variables and calculated odds ratios with 95% CIs.

RESULTS

Five of seven NSF patients receiving MR contrast material had infections at the time of contrast administration. Three hundred thirty-four patients with renal failure received MR contrast material in 2005 and 2006 (29 infected). The rate of NSF was 6.7% in infected renal failure patients and 0.26% in uninfected patients. Data extrapolated to 2002-2006 yielded estimates of 75 infected and 750 uninfected renal failure patients. The association of NSF with infection was highly significant (p < 0.001) with an odds ratio of 25 and CI of 3.9-264.4.

CONCLUSION

The association of NSF with infection was highly significant, supporting the hypothesis that infection at the time of MR contrast administration in renal failure patients predisposes to NSF.

Nephrogenic systemic fibrosis: chronic imaging findings and review of the medical literature

Nephrogenic systemic fibrosis (NSF) is a systemic fibrosing disorder which has been strongly associated with exposure to gadolinium-based contrast media (GBCM) in the setting of renal insufficiency. Although this disorder primarily affects the skin, it can result in severe joint contractures, disabilities and even death. However, to date, there have been no published studies reporting chronic imaging findings of NSF. In this report we present three biopsy-proven cases of NSF with the associated chronic MRI, radiographic and bone scintigraphy findings. Two of the patients had been exposed to gadodiamide, and one had been exposed to gadopentetate dimeglumine prior to the onset of NSF. Two are newly reported cases. One patient's subacute imaging findings have previously been reported, but significant chronic images will now be presented. This patient became severely disabled from contractures and developed long bone smooth periosteal reaction, extensive intra-articular and periarticular calcifications, musculotendinous heterotopic ossification and ankylosis of several joints. One of the patients underwent renal transplantation 6 months after GBCM exposure, with near complete resolution of the skin fibrosis. The third patient had persistent MRI findings of skin thickening, with low T1 and high T2 signal intensity 5 years after exposure to gadodiamide. A review of the medical literature is provided, emphasizing the association of NSF with various GBCM. These cases broaden our understanding of the long-term imaging findings and complications of NSF and the stratified risk of NSF with various GBCM.

The impact of NSF on the care of patients with kidney disease

The association of nephrogenic systemic fibrosis (NSF) with the use of gadolinium-based magnetic resonance contrast agents (GBMCAs) has greatly affected the care of patients with kidney disease. Nephrogenic systemic fibrosis has been reported in patients with end-stage renal disease, chronic kidney disease (CKD) and acute kidney injury. The majority of cases have occurred in patients with end-stage renal disease, but cases of NSF have been reported in CKD patients with glomerular filtration rates less than 30 mL/min/1.73 m(2). Odds ratios have ranged between 8.97 and 32.5 among patients exposed to GBMCAs. Given the significant morbidity, disability, and mortality associated with NSF, it is imperative to properly and preemptively identify those patients at risk. Patients with end-stage renal disease seem to be at highest risk, particularly those maintained on peritoneal dialysis (PD). Although there are no data to support a role for hemodialysis in reducing the risk for NSF after the administration of GBMCAs, hemodialysis is recommended within 2 to 3 hours. Patients maintained on PD and those with CKD present a challenge, as they do not typically have vascular access for hemodialysis, yet the clearance of GBMCAs is very low, and it may be prudent to consider hemodialysis especially for PD patients. Gadolinium-based magnetic resonance contrast agents are removed by dialysis, with estimates that about 99% of a dose is removed after 3 to 4 sessions of hemodialysis. The elimination half-life averaged 9 hours in patients with stage 4 CKD (glomerular filtration rate <30 mL/min/1.73 m(2)) compared with 1.5 hours in those with normal glomerular filtration rates. This prolonged elimination and longer exposure may be important factors in predisposing to NSF.

Clinical and histological findings in nephrogenic systemic fibrosis

Nephrogenic systemic fibrosis (NSF) is a relative newcomer to the world of medicine. NSF was introduced just over 10 years ago as nephrogenic fibrosing dermopathy, but with further investigation, its systemic nature was determined. The strict adherence to a definition requiring both clinical and pathological concordance has allowed for careful separation of this entity from other fibrosing disorders, leading eventually to the realization that gadolinium-based contrast agents were closely associated with its onset. As planned prospective studies get underway, it is of paramount importance that researchers and clinicians realize that NSF remains a very challenging diagnosis, and that both clinical and histopathological criteria must be employed to reach the most accurate diagnosis possible.

Patient characteristics and risk factors for nephrogenic systemic fibrosis following gadolinium exposure

Nephrogenic systemic fibrosis (NSF) is a systemic illness, which only affects patients with kidney failure. NSF risk increases with progressively lower levels of kidney function. It is characterized by red skin areas or plaques that develop over several weeks to painful thickened skin with a "woody" texture, resembling "peau d'orange." It may ultimately cause flexion contractures of joints. Skin biopsy reveals thickened collagen bundles, mucin deposition, proliferation of fibroblasts and elastic fibers, without inflammation. Originally described as nephrogenic fibrosing dermopathy (NFD), because of its primarily cutaneous manifestation, it was renamed NSF because of the involvement of various organs like the lungs, myocardium, or striated muscles. The pathogenesis of the disease is not known yet, but recently we suggested a strong association between development of NSF and exposure to gadolinium-based contrast (GBC) agents, thereafter confirmed by other authors. As a consequence of our recent observations, medical authorities imposed restrictions that exclude patients with advanced levels of renal insufficiency from potentially important magnetic resonance imaging studies with gadolinium. Unfortunately, the only alternatives in many situations (examination of brain, lungs, vasculature) are imaging modalities using iodinated radiocontrast agents. Thus, clinicians are faced with weighing the potential risk of NSF from GBC exposure against the risk of acute kidney injury-associated with radiocontrast media. In this dilemma, clinicians must identify patients at high-risk to develop NSF. Known risk factors critical for the development of NSF after exposure to GBC agents (certain chelates and higher doses) are end-stage renal disease requiring dialysis, especially those with little or no residual renal function, and advanced kidney disease not on dialysis. Other potential risk factors include metabolic acidosis, iron overload/intravenous iron, divalent ion disturbances, endothelial/vascular injury, and high erythropoietin doses. Further studies are required.

Gadolinium and nephrogenic systemic fibrosis: association or causation

With widespread availability of magnetic resonance imaging (MRI), it has become standard practice for patients with severe renal impairment or previous severe reactions to iodine-containing contrast media to receive gadolinium-based MRI contrast agents instead of traditional radiographic contrast agents, particularly for magnetic resonance angiography. However, there is growing concern about the use of gadolinium contrast agents in the presence of severe renal insufficiency, because of increasing reports of nephrogenic fibrosing dermopathy (NFD)/nephrogenic systemic fibrosis (NSF), associated with the exposure to certain gadolinium-containing contrast agents. In this review we explore the causal link between gadolinium exposure and NSF, using an established system of epidemiological criteria proposed by Bradford Hill. Though the current evidence makes gadolinium a strong suspect as an aetiologic agent for NSF in the presence of severe renal failure, the die is not cast yet. At this stage there needs to be cautious approach to the use of gadolinium-containing contrast agents in the presence of severe renal failure (glomerular filtration rate <30 mL/min per 1.73 m(2)).

Gadolinium is not the only trigger for nephrogenic systemic fibrosis: insights from two cases and review of the recent literature

Nephrogenic systemic fibrosis (NSF) is an emerging fibrosing disease with serious consequences in patients with acute and chronic kidney disease including solid organ and renal transplant recipients. It has recently been linked to gadolinium exposure. Almost all recently reported cases of NSF were found to be preceded by gadolinium administration, which led the FDA to issue a warning against the use of gadolinium in patients with moderate-to-severe reduction in the glomerular filtration rate. We report two organ transplant recipients who developed NSF and in whom extensive record review failed to document any prior gadolinium exposure. We then critically review the recently published literature linking NSF and gadolinium and we propose other possible triggers. We conclude that gadolinium is not the only trigger for NSF, and that the search for other triggers should be sought. We believe that this information is an important addition to the NSF literature, such that the definitive etiology and pathogenesis of NSF can be researched.