SDMRad

 Radiological Findings, Disease course, and Management

 

 Intravenous Pyelogram (IVP)

 

 

 

 

 

 

 

 

 

   

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Findings

Scout Film.

• Both the renal shadows are obscured by bowel gas. The right renal outline is partially visualised, laterally renal outline is seen to extend upto the properitoneal fat line….suggestive of nephromegaly

• Multiple abnormal radio-opaque shadows seen scattered in the region of right kidney and right lumbar region suggestive of renal calculi . Largest calculus measures 15 x 8 mm , possibly in the region of pelvis…? Staghorn calculus.

Intravenous Urogram.

 

• Right Kidney

    Nephrogram  / contrast excretion is not seen on the right side even on     delayed films (4 hours delayed film ).

 

• Left Kidney  

    Shows normal pelvi-calyceal pattern and normal ureter with prompt           excretion of contrast by the left  Kidney.

 

• Urinary bladder appears normal without significant post void residue

IMPRESSION

• Absent nephrogram with absent contrast excretion on the right side

• Right nephromegaly with multiple right renal calculi

• Normal left kidney and urinary bladder.

 

    Findings are suggestive of pyelonephritis/ Xanthogranulomatous               pyelonephritis of the right kidney.

 

 Ultrasound KUB region                                        

                                                  

 

 

 

 

 

 

 

 

 

 

 

 

  Findings

• Patient comfortable, not toxic. No probe tenderness in right lumbar region.

• Right kidney appears diffusely enlarged with globular outline, measuring 96 x 60 mm showing multiple calculi with a stag horn calculus in the region of pelvis, measuring 13 mm.

• Calyces are dilated and filled with multiple fluid filled masses and  echogenic debris.

• Left kidney and Urinary bladder appear normal  

 

Clinical course

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No biopsy done.

No follow up available as patient was not admitted at our hospitalfor further management

 

Discussion

   Background

• Xanthogranulomatous pyelonephritis is an uncommon chronic suppurative renal infection characterized by destruction of renal parenchyma and replacement with lipid-containing macrophages

• Two forms of XP are well known,

    a diffuse form (85%) and

    a focal form (15%)- also known as "tumefactive" form.

• Predominantly affects adults in the 5th through 7th 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.

• Nephrolithiasis, and staghorn calculi are found in approximately one-half of patients.

• Patients are usually symptomatic, but with non-specific clinical manifestation like recurrent low-grade fever, malaise, flank pain, hematuria and prior urinary tract infection

• 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, P. mirabilis and E. coli the most           common organisms implicated. 

  

 Diagnosis

 Imaging findings

1. Diffuse Xanthogranulomatous Pyelonephritis

• CT very helpful for diagnosis and surgical planning of this form of XP

• frequently demonstrates characteristic features and depicts extension of the inflammatory process beyond the kidney.

• Abdominal radiography, intravenous urography and ultrasound images show less conclusive features.

• Abdominal radiograph

    large staghorn calculus is present in most cases

    enlargement of the affected kidney 

    if extrarenal extension exists,obscuration of the ipsilateral psoas muscle

• Excretory urography

    decrease in renal function on the pathological side is observed,

    delay on the contrast material excretion or no excretion

• Ultrasound

    demonstrates an enlarged kidney, with multiple fluid collections replacing     the normal corticomedullary differentiation

    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

    diffuse enlargement of kidney

    replacement of renal parenchyma by multiple low-attenuation rounded       masses (dilated calyces or focal areas of parenchyma destruction)

    central calcification within a contracted renal pelvis

    Extrarenal extension may be seen, involving the perirenal space,             pararenal spaces, ipsilateral psoas muscle, posterior abdominal wall, skin     or bowel

    Less common CT features are absence of calculi (up to 10% of cases),       pelvic dilatation or renal atrophy.

• MR

    Features are similar to CT 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

 

 2.  Focal Xanthogranulomatous Pyelonephritis

• 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.

• Ultrasonographic features of focal XP and those of renal tumors or abscesses extensively overlap. The focal disease may be seen as a hypoechoic mass with an associated calculus.

• CT is the imaging modality of choice. A focal intrarenal mass with fluid like attenuation and rim enhancement is seen, often with an associated calculus Extension to extrarenal spaces is possible as well.  

 

Differential diagnosis

• CT: 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 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.

  Conclusion

• CT : gold standard technique in the diagnosis of XP

• It demonstrates highly specific intrarenal findings in the majority of cases (diffuse XP) and shows extrarenal extension, useful for surgical planning.

• 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.

 

  References

• M, BARRAI et al. "XANTHOGRANULOMATOUS PYELONEPHRITIS: Radiologic Review.". N.p., 2014. Web. 31 Mar. 2017.