[Hyperphosphatemic pseudotumoral calcinosis due to FGF23 mutation with secondary amyloidosis].

A 44 years old man was admitted for nephrotic syndrome and rapidly progressive renal failure. Two firm, tumour-like masses were localized around the left shoulder and the right hip joint. Since the age of 8 years old, the patient had a history of metastatic calcification of the soft tissues suggesting hyperphosphatemic pseudotumoral calcinosis. Despite treatment for a long time with phosphate binders the metastatic calcinosis had to be removed with several surgeries. The patient had also a history of recurrent fever associated with pain localized toward the two masses and underwent multiple antibiotic courses. Laboratory findings at admission confirmed nephrotic syndrome. S-creatinine was 2.8 mg/dl. Calcium was 8.4 mg/dl, Phosphorus 8.2 mg/dl, PTH 80 pg/ml, 25 (OH)VitD 8 ng/ml. Serum amyloid A was slightly increased. We performed renal biopsy and we found AA amyloid deposits involving the mesangium and the tubules. The bone marrow biopsy revealed the presence of AA amyloid in the vascular walls. During the next two months renal failure rapidly progressed and the patient started hemodialysis treatment. We performed genetic analysis that confirmed homozygous mutation of the FGF23 gene. After 14 months on hemodialysis, the patient's lesions are remarkably and significantly reduced in dimension. The current phosphate binder therapy is based on sevelamer and lanthanum carbonate. Serum amyloid A is persistently slightly increased as well as C reactive protein. Proteinuria is in the nephrotic range without nephrotic syndrome.

[Vascular access survey in the Triveneto area: data analysis for the year 2017].

In 2017 the Italian Society of Nephrology operating in the Triveneto area investigated through a questionnaire, distributed to the various nephrological centers in the regions of Friuli Venezia Giulia, Trentino Alto Adige and Veneto, the differences concerning organizational models, choice of dialysis, creation and management of vascular access. The results emerging from the analysis of the collected data are presented.

Central Venous Stenosis after Hemodialysis: Case Reports and Relationships to Catheters and Cardiac Implantable Devices.

The appropriate vascular access for hemodialysis in patients with cardiac implantable electronic devices (CIED) is undefined. We describe two cases of end-stage renal disease patients with CIED and tunneled central venous catheter (CVC) who developed venous cava stenosis: (1) a 70-year-old man with sinus node disease and pacemaker in 2013, CVC, and a Brescia-Cimino forearm fistula in 2015; (2) a 75-year-old woman with previous ventricular arrhythmia with implanted defibrillator in 2014 and CVC in 2016. In either case, after about 1 year from CVC insertion, patients developed superior vena cava (SVC) syndrome due to stenosis diagnosed by axial computerized tomography. In case 1, the patient was not treated by angioplasty of SVC and removed CVC with partial resolving of symptoms. In case 2, a percutaneous transluminal angioplasty with placement of a new CVC was required. To analyze these reports in the context of available literature, we systematically reviewed studies that have analyzed the presence of central venous stenosis associated with the simultaneous presence of CIED and CVC. Five studies were found; two indicated an increased incidence of central venous stenosis, while three did not find any association. While more studies are definitely needed, we suggest that these patients may benefit from epicardial cardiac devices and the insertion of devices directly into the ventriculus. If the new devices are unavailable or contraindicated, peritoneal dialysis or intensive conservative treatment in older patients may be proposed as alternative options.

Quantification of fibrin in blood thrombi formed in hemodialysis central venous catheters: a pilot study on 43 CVCs.

PURPOSE: Fibrin deposition and thrombotic occlusion represent a serious cause of access dysfunction in hemodialysis central venous catheters (CVCs). The aim of this work was to define and apply a method for imaging and quantifying fibrin in thrombi formed into the side holes of CVCs. METHODS: Forty-three CVCs removed from a cohort of dialyzed patients were analyzed in this pilot study. Hematoxylin and eosin and a modified Carstair's staining were applied on permanent thrombus sections. Fluorescence microscopy and image analysis were performed to quantify the fibrin amount. RESULTS: Highly fluorescent areas were invariably associated with fibrin by Carstair's method. The deposition of concentric layers of fibrin and erythrocytes was easily identified by fluorescence microscopy, showing growth features of the thrombus. Fibrin amount in diabetic patients was significantly higher than that in nondiabetic patients with median (interquartile range) values of 51% (47-68%) and 44% (30-54%), respectively (p=0.032). No significant difference in fibrin content was found by grouping data according to catheter type, permanence time, insertion site and dialysis vintage. Higher variability in fibrin values was found in thrombi from CVCs removed after 1-15 days compared with 16-60 days. A trend of an increase in fibrin amount in thrombi was noted according to blood platelet count at CVC insertion. CONCLUSIONS: The analytical method presented here proved to be a rapid and effective way for quantifying fibrin content in thrombi formed on CVCs with potential application in future clinical studies.

Vascular access in older patients: an Italian survey.

BACKGROUND: The number of older patients starting hemodialysis is continuously increasing. The type of vascular access plays an important role in dialysis treatment, but it can be difficult to create in older patients. METHODS: This study compared vascular access survival rates and patient survival rates in older (≥65 years) and younger (<65 years) patients starting hemodialysis in 2 Italian hospitals in 2006-2008. RESULTS: The study enrolled 336 patients: 208 ≥65 years and 128 <65 years of age. The vascular accesses used, in order of frequency, were 102 distal arteriovenous fistulas (dAVFs) (49%), 55 midarm AVFs (pAVFs) (26%), 9 arteriovenous grafts (AVGs) (4%) and 42 central venous catheters (CVCs) (20%) in the older patients, and 89 dAVFs (69%), 25 pAVFs (19%), 6 AVGs (5%) and 8 CVCs (6%) in the younger patients. Survival rates of fistula and catheter did not differ between the 2 groups. AVGs failed earlier (p = 0.02) in the older patients. On Cox analysis, age (hazard ratio [HR] = 1.073; p<0.001) and CVC (HR = 4.152; p<0.001) increased the risk of death. CONCLUSION: A fistula is the gold standard for hemodialysis vascular access in older patients if judged appropriately.

Hemodialysis catheter thrombi: visualization and quantification of microstructures and cellular composition.

PURPOSE: Despite the increasing use of central venous catheters (CVC) for hemodialysis in clinical practice, the role of CVC in thrombus development is poorly understood. This work aims at defining new methods and protocols for assessing the micromorphology and composition of thrombi formed into tunneled and non-tunneled hemodialysis CVC removed from patients. 
 METHODS: Twenty-nine CVCs were collected and the microscopic features of intra-luminal thrombi were quantified by scanning electron microscopy (SEM) and visualized by two photon laser scanning microscopy (TPLSM). 
 RESULTS: SEM quantification showed that fibrin was the most abundant structure in CVC thrombi. Specifically, the median micromorphologic composition of the surface layer resulted in: 42.6% of fibrin plaque, 16.3% of fibrin network, 0.4% of fibrin fibers, 9.3% of platelets, 10.3% of erythrocytes and 1.7% of white blood cells. TPLSM showed that sub-surface layers were instead composed by smaller amounts of fibrin and platelets and higher amounts of blood cells.
 CONCLUSIONS: Integration of SEM and TPLSM was found to be an excellent tool for characterizing thrombi in hemodialysis CVC removed from patients. Protocols and techniques presented here may be useful in the development and testing of new strategies for limiting thrombus formation on vascular access because of CVC.