XANTHOGRANULOMATOUS PYELONEPHRITIS: radiologic review.

Transcription

1 XANTHOGRANULOMATOUS PYELONEPHRITIS: radiologic review. Poster No.: C-0557 Congress: ECR 2014 Type: Educational Exhibit Authors: M. Barral, J. M. Sánchez Crespo, J. C. Pérez Herrera, J. L Ortega Garcia, F. J. Hidalgo Ramos, G. Porcuna Cazalla ; Puerto Real/ES, Vejer de la Frontera, Cádiz/ES, Jerez de la Frontera/ES Keywords: Infection, Calcifications / Calculi, Diagnostic procedure, Ultrasound, CT, Conventional radiography, Kidney, Abdomen DOI: /ecr2014/C-0557 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 20

2 Learning objectives - To illustrate radiological findings of xanthogranulomatous pyelonephritis (XP) on different imaging techniques. - To learn when to include XP as a diagnostic possibility, according to the clinical context and the radiological features. Page 2 of 20

3 Background Xanthogranulomatous pyelonephritis is an uncommon chronic suppurative renal infection characterized by destruction of renal parenchyma and replacement with lipid-containing macrophages (fig. 1). Two forms of XP are well known, a diffuse form (85%) and a focal form (15%), the latter also known as "tumefactive" form. th th It predominantly affects adults in the 5 through 7 decades of life and female gender is more frequently affected. Typically, there is a unilateral and diffuse affectation of the kidney and extension to the perirenal spaces is common. Most patients have nephrolithiasis, and staghorn calculi are found in approximately one-half of patients. Patients are usually symptomatic, but with non-specific clinical manifestation; most of them have recurrent low-grade fever, malaise, flank pain, hematuria and prior urinary tract infection (fig. 2). Laboratory studies show an elevated erythrocyte sedimentation rate, anemia, and leukocytosis. More than 80% of patients with XP have pyuria and over 60%, positive urine cultures, being P. mirabilis and E. coli the most common organisms implicated. The percentage of sterile urine cultures found is explained by the complete obstruction of the kidney and bladder seen in some cases. An early diagnosis of this pathology brings excellent results after surgery. Page 3 of 20

4 Images for this section: Fig. 1: Microscopic features of xanthogranulomatous pyelonephritis. Original (a) and greater (b) magnification show lipid-laden macrophages (blue arrow) intermingled with leukocytes and plasma cells (yellow arrow) in the renal medulla. Red arrow shows a glomerulus in a thinned renal cortex. Page 4 of 20

5 Fig. 2: Frequent clinical findings of XP. Page 5 of 20

6 Findings and procedure details Imaging findings # Diffuse Xanthogranulomatous Pyelonephritis CT technique deserves a special attention because it will be very helpful for diagnosis and surgical planning on this form of XP. It frequently demonstrates characteristic features and depicts extension of the inflammatory process beyond the kidney. In the other hand, abdominal radiography, intravenous urography and ultrasound images will show less conclusive features. Abdominal radiography The radiographic finding of a large staghorn calculus is present in most cases, but this feature by itself is nonspecific. Additional findings include enlargement of the affected kidney and, if extrarenal extension exists, obscuration of the ipsilateral psoas muscle (fig. 3, 4, 9). Excretory urography An important decrease in renal function on the pathological side is observed, with a delay on the contrast material excretion or with no excretion (fig. 3). Ultrasound This technique demonstrates an enlarged kidney, with multiple fluid collections replacing the normal corticomedullary differentiation (fig. 6). These collections are either anechoic or hypoechoic areas and correspond to dilated calyces and areas of parenchymal destruction. An echogenic pelvis from a central staghorn calculus may be seen. Perirenal extension is observed as hypoechoic fluid masses. CT Page 6 of 20

7 Typical findings are diffuse enlargement of kidney, replacement of renal parenchyma by multiple low-attenuation rounded masses (dilated calyces or focal areas of parenchyma destruction) and a central calcification within a contracted renal pelvis (fig. 4, 7, 8, 9). Extrarenal extension may be seen, involving the perirenal space, pararenal spaces, ipsilateral psoas muscle, posterior abdominal wall, skin or bowel (fig. 5, 7). Less common CT features are absence of calculi (up to 10% of cases), important pelvic dilatation or renal atrophy. MR This technique does not give any advantage compare to CT. Features are similar to the ones described on CT paragraph; enlarged kidney, replacement of renal parenchyma by abscess cavities with intermediate signal intensity on T1-weighted images and high signal intensity on T2-weighted images. Calculi are better depicted with CT but may be seen at MR imaging as areas of signal void within the renal pelvis (fig. 10). # Focal Xanthogranulomatous Pyelonephritis This infrequent form of XP is confined to a part or pole of the kidney. Findings may not be similar to the ones described for diffuse XP and no single radiological sign is pathognomonic. The definitive diagnosis of focal XP is most often given after histologic examination of the surgical specimen. Ultrasound Ultrasonographic features of focal XP and those of renal tumors or abscesses are extensive overlap. The focal disease may be seen as a hypoechoic mass with an associated calculus. CT It is the imaging modality of choice. A focal intrarenal mass with fluidlike attenuation and rim enhancement is seen, often with an associated calculus (fig. 11). Extension to extrarenal spaces is possible as well. Page 7 of 20

8 Differential diagnosis CT examination demonstrates highly specific intrarenal findings in the majority of cases of diffuse form of XP. Differentiating XP from other types of renal infection or a renal neoplasm becomes very difficult when atypical findings are seen or in case of focal form of XP. Differential diagnosis for diffuse form of XP must include pyonephrosis (fig. 8) and hydronephrosis. Imaging findings of focal XP may imitate those of neoplastic diseases (such as renal cell carcinoma, lymphoma, or leukemia in adults and Wilm tumor in children) and other focal inflammatory renal parenchymal diseases (such as renal tuberculosis, renal abscess, and malakoplakia). Treatment and prognosis Treatment consists on total nephrectomy for diffuse XP. The treatment of focal XP is controversial. In selected cases, partial nephrectomy has been tried. There are also reports of a few patients who recovered from the disease after antibiotic therapy. The prognosis is excellent, and XP does not recur after surgery. Page 8 of 20

9 Images for this section: Fig. 3: 43-year-old woman with recurrent right flank pain. Abdominal radiography (a) demonstrates a large staghorn calculus in the left kidney. On excretory urogram (b) and delayed phase (c), nonfunction of the left kidney is demonstrated. Page 9 of 20

10 Fig. 4: 37-year-old man with a 2-weeks history of progressive right flank pain, malaise and high-grade fever. On abdominal radiography, a large staghorn calculus in the right kidney is observed without being able to delimitate its upper pole profile, neither the left kidney profile. CT scan with contrast material in venous (b) and excretory (c) phases show a horseshoe kidney with typical features of xanthogranulomatous pyelonephritis; a diffuse enlargement of the right kidney, a replacement of renal parenchyma by multiple low-attenuation rounded masses and a central calcification. On the excretory phase, no contrast material excretion is demonstrated on the right kidney, being excretion on the left kidney normal (white arrow). Page 10 of 20

11 Fig. 5: CT scan of the same patient of figure 4 reveals posterior perirenal (green arrow) and pararenal (white arrow) extension of the inflammatory process. Page 11 of 20

12 Fig. 6: 38-year-old woman with left flank pain, fever and altered renal function. Ultrasound technique of the right kidney (a) is normal. Left kidney (b, c) is enlarged, with some fluid collections replacing the normal corticomedullary differentiation and with an echogenic pelvis associated to a posterior acoustic shadowing from a central staghorn calculus. Page 12 of 20

13 Fig. 7: Same patient as in figure 6. CT scan confirms typical features of diffuse XP in the left kidney. Extrarenal affection is seen as well on (d, e) with a fluid collection in the perirenal space (green arrow) and infiltration of the lumbar quadrate muscle (blue arrow). Page 13 of 20

14 Fig. 8: 59-year-old woman with right flank pain and high-grade fever. On CT scan (a-c), right kidney is enlarged, with a staghorn calculus (specially in the lower pole of the kidney) and multiple fluid collections replacing the normal parenchyma. Left kidney has a normal size, shows a staghorn calculus and fluid collections as well. The diagnosis of suspicious was bilateral xanthogranulomatous pyelonephritis, obtaining after right nephrectomy an histological result of XP complicated by pyonephrosis. Page 14 of 20

15 Fig. 9: Same patient as in figure 8 after three years. Abdominal radiography (a, b) demonstrates changes secondary to right nephrectomy and staghorn calculus on the left kidney. CT scan (c, d) confirms same features, and shows the presence of multiple fluid collections replacing the normal corticomedullary differentiation. Page 15 of 20

16 Fig. 10: Same patient as in figure 8 and 9. MRI; T2-weighted images on axial (a-c) and coronal (d-g) planes. Replacement of renal parenchyma by abscess cavities with high signal intensity on T2-weighted images. Calculi are seen as areas of signal void within the renal pelvis and calyces. Page 16 of 20

17 Fig. 11: 62-year-old woman with right flank pain. CT scan shows a mass with areas of fluidlike with an associated calculus located in the upper pole of the right kidney. The diagnosis of suspicious was renal cell carcinoma. After nephrectomy, histological result was focal xanthogranulomatous pyelonephritis. Page 17 of 20

18 Conclusion - CT is the gold standard technique in the diagnosis of XP for two reasons: it demonstrates highly specific intrarenal findings in the majority of cases (diffuse XP) and shows extrarenal extension, useful for surgical planning. - It will be difficult to differentiate XP from other types of renal infection or a renal neoplasm when atypical findings are seen or in case of focal form of XP. Page 18 of 20

19 Personal information Page 19 of 20

20 References Hayes WS, Hartman DS, Sesterbenn IA. Xanthogranulomatous pyelonephritis. RadioGraphics 1991; 11: Craig WD, Wagner BJ, Travis MD. Pyelonephritis: radiologic-pathologic review. RadioGraphics 2008; 28: Pedrosa IP, Sun MR, Spencer M, Genega EM, Olumi AF, Dewolf WC, Rofsky NM. MR imaging of renal masses: correlation with findings at surgery and pathologic analysis. RadioGraphics 2008; 28: Muta T, Takamatsu Y, Morita S, Kikuchi I, Tamuro K. Xanthogranulomatous pyelonephritis. Internal Medicine 1997; 36: Fan CM, Whitman GJ, Chew FS. Xanthogranulomatous pyelonephritis. AJR 1995; 165:862. Kim J. Ultrasonographic features of focal xanthogranulomatous pyelonephritis. J Ultrasound Med 2004; 23: Ramboer K, Oyen R, Verellen S, Vermeersch S, Baert AL, Verberckmoes R. Focal xanthogranulomatous pyelonephritis mimicking a renal tumor: CTand MR-findings and evolution under therapy. Nephrol Dial Transplant 1997; 12: Page 20 of 20