Imaging Features of Encapsulating Peritoneal Sclerosis in Continuous Ambulatory Peritoneal Dialysis Patients

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1 Genitourinary Imaging Pictorial Essay Ti et al. Encapsulating Peritoneal Sclerosis in CPD Patients Genitourinary Imaging Pictorial Essay Joanna P. Ti 1 li l-radi 2 Peter J. Conlon 2 Michael J. Lee 1 Martina M. Morrin 1 Ti JP, l-radi, Conlon PJ, Lee MJ, Morrin MM Keywords: CPD, continuous ambulatory peritoneal dialysis, encapsulating peritoneal sclerosis, peritoneal calcification, peritoneal fibrosis, sclerosing encapsulating peritonitis DOI: /JR Received June 15, 2009; accepted after revision December 29, Department of Radiology, eaumont Hospital, eaumont Rd., Dublin 9, Ireland. ddress correspondence to J. P. Ti (joanna_ti@eircom.net). 2 Department of Nephrology and Renal Transplantation, eaumont Hospital, Dublin, Ireland. WE This is a Web exclusive article. JR 2010; 195:W50 W X/10/1951 W50 merican Roentgen Ray Society Imaging Features of Encapsulating Peritoneal Sclerosis in Continuous mbulatory Peritoneal Dialysis Patients OJEIVE. The purpose of this article is to present the spectrum of radiologic findings of encapsulating peritoneal sclerosis in patients undergoing continuous ambulatory peritoneal dialysis (CPD). CONCLUSION. lthough a rare diagnosis, encapsulating peritoneal sclerosis in patients undergoing CPD has a high morbidity and mortality. Diagnosis is often delayed because clinical features are insidious and nonspecific. Radiologic imaging may be helpful in the early diagnosis of encapsulating peritoneal sclerosis and in facilitating timely intervention for CPD patients with encapsulating peritoneal sclerosis. E ncapsulating peritoneal sclerosis, also referred to as sclerosing encapsulating peritonitis, is now a well recognized but uncommon serious complication of continuous ambulatory peritoneal dialysis (CPD) [1]. The exact cause of encapsulating peritoneal sclerosis is unknown; however, multiple possible contributing factors have been implicated including the duration of time on peritoneal dialysis, recurrent episodes of bacterial peritonitis, the use of glucose-based dialysate, the presence of endotoxin from bacterial filters, and the use of chlorhexidine [2]. In a large study by Rigby and Hawley [2], the overall prevalence of encapsulating peritoneal sclerosis was 0.7%; however, the prevalence increases to 19.4% in patients on CPD for more than 8 years [2]. lthough this condition is more commonly referred to as sclerosing encapsulating peritonitis, the term encapsulating peritoneal sclerosis is thought to more accurately describe the morphologic changes [3]. Encapsulating peritoneal sclerosis in patients undergoing CPD is a condition characterized by fibrotic thickening of the peritoneum. The peritoneum may be opaque, thickened, tanned, or leathery to the naked eye [2]. The thickened, abnormal peritoneum can progress to encase, or encapsulate, small-bowel loops with resultant bowel obstruction when the small-bowel loops eventually become trapped by the fibrotic peritoneum. This process is aggravated if the fibrotic process invades the outer aspect of the wall of the small bowel and causes mural fibrosis [4]. Encapsulating peritoneal sclerosis is associated with significant morbidity and mortality primarily because of acute or subacute small-bowel obstruction, with resultant gut failure and malnutrition, sepsis, and death. In a study by Rigby and Hawley [2], the mortality rate associated with encapsulating peritoneal sclerosis was 56%. Diagnosis is made radiologically or surgically; however, the diagnosis of encapsulating peritoneal sclerosis is often delayed because the clinical features are nonspecific and insidious and may mimic those of the more common diagnosis of bacterial peritonitis. Radiologic imaging may facilitate an early diagnosis of encapsulating peritoneal sclerosis to enable appropriate management. The imaging features of encapsulating peritoneal sclerosis can be divided into peritoneal abnormalities, small-bowel abnormalities, and loculated fluid collections [5]. In this article, we present the spectrum of radiologic findings in encapsulating peritoneal sclerosis and show the progression of disease in one of our patients. Radiologic mimics of encapsulating peritoneal sclerosis include causes of peritoneal calcification, such as pseudomyxoma peritonei; tuberculosis; peritoneal mesothelioma; and calcified peritoneal carcinomatosis. In neonates, meconium peritonitis can mimic encapsulating peritoneal sclerosis [6]. W50 JR:195, July 2010

2 Encapsulating Peritoneal Sclerosis in CPD Patients It is important to diagnose encapsulating peritoneal sclerosis at an early stage because it is important to discontinue peritoneal dialysis once there is a suspicion of development of encapsulating peritoneal sclerosis. Curative treatment of established encapsulating peritoneal sclerosis is surgical excision of the thickened peritoneum and adhesiolysis; however, surgery is high risk in these patient groups, and successful outcomes are more likely in specialist centers [1]. Occasionally, resection of nonviable bowel is necessary. Other less effective treatments include immunosuppression with prednisolone, sirolimus, or tamoxifen; more conservative measures include cessation of peritoneal dialysis and bowel rest with total parenteral nutrition [1, 7]. Peritoneal bnormalities In encapsulating peritoneal sclerosis, an inflammatory process affects the peritoneum diffusely, resulting in widespread peritoneal fibrosis. This manifests as peritoneal thickening, which can be smooth or irregular and nodular. Contrast-enhanced examinations show enhancement of the thickened peritoneum (Figs. 1 and 2). The peritoneal thickening progresses to peritoneal encapsulation of the involved small-bowel loops a process that has been described as cocooning of the small bowel by a sheath of fibrous, sclerosed peritoneum [2] (Figs. 1 and 2C). Peritoneal calcification begins as a small plaque that gradually becomes widespread [8], involving both visceral and parietal peritoneum [4]. The visceral peritoneal calcification has also been described as bowel wall serosal or mural calcification or as sclerosing serositis [7] (Figs. 2 and 3). bdominal Radiography Widespread peritoneal calcification can be identified on abdominal radiographs [9] (Fig. 4). However, diffuse peritoneal calcification is mainly associated with advanced encapsulating peritoneal sclerosis, and advanced encapsulating peritoneal sclerosis may also occur in the absence of peritoneal calcification (Fig. 5). Typically, mild peritoneal thickening progresses to diffuse, severe peritoneal thickening and eventually to peritoneal calcification. With a high index of suspicion, the irregular nodular peritoneal thickening visualized on the initial examination can raise the possibility of encapsulating peritoneal sclerosis and, hence, may prompt cessation of peritoneal dialysis. Small-owel bnormalities Small-bowel dilatation occurs in encapsulating peritoneal sclerosis as the sclerosed, thickened peritoneum surrounds the small-bowel loops, leading to bowel obstruction. Varying lengths of small bowel may be tightly enclosed within pockets of fibrotic peritoneum [4]. This phenomenon has been described as a cocoon of thickened peritoneum that traps small-bowel loops within it; the term cocoon has also been described to occur in other rare conditions [4]. The small-bowel loops are often collected centrally by the encapsulating fibrotic peritoneum (Figs. 2C, 5, and 6). The diffuse inflammatory fibrotic process may progress to involve the outer aspect of the wall of the small bowel, leading to mural fibrosis, thickening of the small-bowel wall (Fig. 2C), adherent bowel loops, narrowing of the bowel lumen, and proximal bowel obstruction [7] (Figs. 1, 2C, and 7). The fibrotic process may manifest as a mass of small-bowel loops tethered together. Ultimately, small-bowel necrosis with perforation may occur [4, 6] (Fig. 3). Ultrasound owel wall thickening has a trilaminar appearance on ultrasound [8] (Fig. 8). lthough small-bowel obstruction can be identified on abdominal radiographs, examination yields additional information such as thickening of the small-bowel wall and the exact site and cause of obstruction. Fluid Collections Imaging Patients on CPD inevitably have dialysate fluid within the abdomen and pelvis. Hence, the presence of free fluid during radiologic investigations in these patients is nonspecific. In encapsulating peritoneal sclerosis, the fibrotic, thickened peritoneal membranes can result in loculated ascites [2] (Figs. 6 and 7). s the small bowel becomes involved, tethered and masslike, the tethered small bowel too may produce loculated fluid collections. The fluid collections can increase markedly in size as the disease progresses, as shown in one of our patients who had serial examinations (Fig. 2). In addition, the large fluid collections may contribute to the central location of the tethered small-bowel loops by way of mass effect (Figs. 5 and 6). Conclusion Encapsulating peritoneal sclerosis is an uncommon but significant complication in patients on CPD. This condition is often progressive and can be fatal. n increased awareness and knowledge of the spectrum radiologic findings of encapsulating peritoneal sclerosis may allow early diagnosis of encapsulating peritoneal sclerosis and, hence, early management of patients with withdrawal of peritoneal dialysis and peritonectomy. Early imaging diagnosis of encapsulating peritoneal sclerosis is important because the clinical symptoms of encapsulating peritoneal sclerosis are insidious and nonspecific. References 1. Kawaguchi Y, Saito, Kawanishi H, et al. Recommendations on the management of encapsulating peritoneal sclerosis in Japan, 2005: diagnosis, predictive markers, treatment, and preventive measures. Perit Dial Int 2005; 25[suppl 4]:S83 S95 2. Rigby RJ, Hawley CM. Sclerosing peritonitis: the experience in ustralia. Nephrol Dial Transplant 1998; 13: Holland P. Sclerosing encapsulating peritonitis in chronic ambulatory peritoneal dialysis. Clin Radiol 1990; 41: Kawaguchi Y, Kawanishi H, Mujais S, et al. Encapsulating peritoneal sclerosis: definition, etiology, diagnosis and treatment. International Society for Peritoneal Dialysis d Hoc Committee on Ultrafiltration Management in Peritoneal Dialysis. Perit Dial Int 2000; 20[suppl 4]:S43 S55 5. Choi JH, Kim JH, Kim JJ, et al. Large bowel obstruction caused by sclerosing peritonitis: contrast-enhanced findings. r J Radiol 2004; 77: Loughrey GJ, Hawnaur JM, Sambrook P. Case report: computed tomographic appearance of sclerosing peritonitis with gross peritoneal calcification. Clin Radiol 1997; 52: George C, l-zwae K, Nair S, et al. Computed tomography appearances of sclerosing encapsulating peritonitis. Clin Radiol 2007; 62: Stafford-Johnson D, Wilson TE, Francis IR, et al. appearance of sclerosing peritonitis in patients on chronic ambulatory peritoneal dialysis (abdominal imaging). J Comput ssist Tomogr 1998; 22: Hare CM. Radiological view of sclerosing peritonitis. Nephrol Dial Transplant 1999; 14: JR:195, July 2010 W51

3 Ti et al. Fig year-old woman previously on continuous ambulatory peritoneal dialysis who presented with symptoms of persistent nausea and vomiting. fter diagnosis of encapsulating peritoneal sclerosis, she underwent peritonectomy, gained 10 kg in weight, and is doing well on hemodialysis., Contrast-enhanced abdominal scan shows fluid within abdomen surrounded by thickened, enhancing peritoneum. Peritoneal thickening (arrows) is smooth and regular., Small-bowel wall is thickened and small-bowel loops are dilated (arrow). Small-bowel loops are enclosed by fibrotic peritoneum. Fig year-old man on continuous ambulatory peritoneal dialysis who presented with nausea and poor appetite. Images shown are axial images from three successive scans at level of calcified left renal cyst. This patient died of gut failure while on total parenteral nutrition., March bdominal scan obtained with only oral contrast material shows irregular, nodular peritoneal thickening (arrow) and no peritoneal calcification. Neither bowel wall thickening nor dilated small-bowel loops are seen. There is diffuse vascular calcification. rrowhead = calcified left renal cyst., pril bdominal scan obtained using oral and IV contrast media shows there has been progression of irregular, nodular peritoneal thickening and shows enhancement (black arrows). Small ill-defined focus of peritoneal calcification (arrowhead) is seen. Thickening of small-bowel wall is present, but small bowel (white arrow) is not dilated. C, May One week after removal of Tenckhoff dialysis catheter, abdominal scan obtained using oral and IV contrast media shows free intraabdominal air. Peritoneal calcification (arrowhead) is more defined and focal. Thickened smallbowel loops (arrow) are also dilated, with encapsulated, central appearance. C W52 JR:195, July 2010

4 Encapsulating Peritoneal Sclerosis in CPD Patients Fig year-old woman on continuous ambulatory peritoneal dialysis who presented with acute abdomen. t laparotomy, there was free air from bowel perforation, presumably secondary to necrosis, and whole bowel was coated with thick cementlike material. Patient recovered to receive cadaveric renal transplant but later died of gut failure while on total parenteral nutrition., scan shows dilated loops of small bowel, with diffuse visceral, mural peritoneal calcification (arrowhead)., scan shows that there are also dense, focal deposits of parietal peritoneal calcification (arrowheads). Fig year-old man with nausea and poor appetite (same patient as in Fig. 2). bdominal radiograph shows multiple curvilinear calcifications. Circular rim calcification (arrowhead) on left is calcified left renal cyst. Serpiginous calcification consistent with vascular calcification (black arrow). Curvilinear calcification on right side of radiograph is peritoneal calcification (white arrow), as seen on examination in Figure 2. Fig year-old man previously on hemodialysis who presented with 3-year history of nonspecific abdominal pain. Patient successfully underwent peritonectomy at specialist center and has since received cadaveric renal transplant and is doing well. Contrast-enhanced abdominal scan shows very extensive amount of ascites, with central location of tethered small-bowel loops. There is apparent cocooning of small-bowel loops by sheath of fibrous, sclerosed peritoneum. No peritoneal calcification was visualized on or at laparotomy. JR:195, July 2010 W53

5 Ti et al. Fig year-old woman previously on continuous ambulatory peritoneal dialysis with 2-week history of abdominal pain, nausea, and vomiting. Patient also received cadaveric renal transplant but died of gut failure on total parenteral nutrition. bdominal scan shows large amount of free fluid (thin arrow). Loculated fluid collection within left paracolic gutter (thick arrow) is seen. Fig year-old woman on continuous ambulatory peritoneal dialysis (CPD) with vague abdominal discomfort and malnutrition. bdominal ultrasound image shows trilaminar bowel wall thickening (arrow). There is also free fluid within abdomen, which is expected finding in patients on CPD. Patient received living related donor kidney and is doing well. Fig year-old woman on continuous ambulatory peritoneal dialysis who presented with severe abdominal pain. Laparotomy was performed as emergency procedure, before. Peritoneum was thickened and fibrosed with multiple adhesions. Contrast-enhanced abdominal scan obtained soon after surgery shows free air peritoneal thickening and enhancement, loculated fluid collections, and small-bowel wall thickening (arrow). Patient successfully underwent adhesiolysis and peritonectomy at specialist center and is doing well on hemodialysis. W54 JR:195, July 2010