Diagnostic Ultrasound - Abdomen and Pelvis
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Diagnostic Ultrasound - Abdomen and Pelvis

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09.07.2019 Views

Multilocular Cystic Nephroma TERMINOLOGY Abbreviations • Multilocular cystic nephroma (MLCN) Synonyms • Cystic nephroma, multilocular cystic renal tumor, cystic hamartoma Definitions • Rare, nonhereditary, benign, cystic renal neoplasm containing epithelial and stromal components IMAGING General Features • Best diagnostic clue ○ Encapsulated multilocular cystic renal mass herniating into renal hilum (renal vein or ureter) • Size ○ Entire lesion: Few cm to > 30 cm (average: 10 cm) ○ Individual locules: Few millimeters to 2.5 cm • Morphology ○ Unilateral solitary cystic mass with thick fibrous capsule ± herniation into renal pelvis Ultrasonographic Findings • Grayscale ultrasound ○ Large, well-defined, multiloculated cystic mass ○ Numerous anechoic cysts with hyperechoic septa ○ Hyperechoic thick fibrous capsule ○ Occasionally more solid-appearing due to numerous tiny cysts causing acoustic interfaces • Color Doppler ○ Fine vessels may be seen within septa • Contrast enhanced ultrasound (CEUS) ○ Contrast uptake within septa and wall CT Findings • Large, well-defined, multiloculated cystic mass, rare calcification, ± capsular enhancement • Distortion of collecting system, ± obstruction • Small locules/proteinaceous material within cysts → may appear as solid mass, nonenhancing MR Findings • T1WI: Multiloculated hypointense mass (clear fluid) with variable signal intensity (blood or protein) • T2WI: Hyperintense (clear fluid) or variable (blood or protein) with hypointense capsule and septa (fibrous tissue) • T1WI C+: Enhancement of thin or thick septa DIFFERENTIAL DIAGNOSIS Cystic Renal Cell Carcinoma (RCC) • Cysts in RCC usually not enclosed by capsule • Enhancing nodules favor RCC over MLCN Mixed Epithelial and Stromal Tumor (MEST) • More solid components, mimicking cystic RCC Cystic Wilms Tumor • Numerous thick septa; thinner in MLCN Localized Cystic Renal Disease • Conglomerate of simple cysts simulating multilocular cystic mass, usually unilateral • Lacks well-defined pseudocapsule around cysts • Renal parenchyma is present between cysts Multicystic Dysplastic Kidney (MCDK) • Nonfunctional kidney replaced by multiple cysts and dysplastic tissue • Sonographically, appears as small kidney consisting of multiple cysts or echogenic kidney if cysts are too tiny to be visualized Simple Renal Cysts • No surrounding capsule PATHOLOGY General Features • Etiology ○ Steroid hormonal influence: Estrogens Staging, Grading, & Classification • WHO classification: Grouped with MEST (mixed epithelial stromal tumors) Gross Pathologic & Surgical Features • Thick fibrous capsule • "Honeycombed" noncommunicating cysts of varying size with intervening septa < 5 mm • No solid component or necrosis CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Hematuria, abdominal/flank pain, palpable mass ○ May be asymptomatic Demographics • Bimodal age and sex distribution ○ Children M:F = 3:1, age 2-4 years old ○ Adults F:M = 8:1, peak age 40-60 years old Natural History & Prognosis • Complications ○ Obstructive uropathy, infection ○ Hemorrhage • Good prognosis following excision ○ Local recurrence usually due to incomplete excision Treatment • Cured with complete surgical excision SELECTED REFERENCES 1. Wood CG 3rd et al: CT and MR Imaging for Evaluation of Cystic Renal Lesions and Diseases. Radiographics. 35(1):125-41, 2015 2. Wilkinson C et al: Adult multilocular cystic nephroma: Report of six cases with clinical, radio-pathologic correlation and review of literature. Urol Ann. 5(1):13-7, 2013 3. Lane BR et al: Adult cystic nephroma and mixed epithelial and stromal tumor of the kidney: clinical, radiographic, and pathologic characteristics. Urology. 71(6):1142-8, 2008 4. Hopkins JK et al: Best cases from the AFIP: cystic nephroma. Radiographics. 24(2):589-93, 2004 Diagnoses: Urinary Tract 475

Acute Pyelonephritis Diagnoses: Urinary Tract IMAGING • Findings of acute pyelonephritis (AP) are almost always asymmetric • Renal enlargement with loss of corticomedullary (CM) differentiationon US and CT • Geographic areas of altered echogenicity on US • Urothelial thickening on US and CT • In general, ultrasound is much more sensitive for causes (obstruction) and complications (abscess) of AP than for AP itself, which is a clinical diagnosis • Many kidneys with pyelonephritis will be sonographically normal • Foci of gas in parenchyma (rare) could indicate emphysematous pyelonephritis; treat as urologic emergency • Altered nephrogram on CT, classically striated, best seen in excretory phase • Microabscesses or areas of necrosis can emerge after 1-2 weeks of infection KEY FACTS PATHOLOGY • Most common organism: Escherichia coli • Route of spread of infection: Ascending (85%) > hematogenous (15%) • Risk factors include obstruction, ureteric reflux, diabetes, pregnancy, lower UTI CLINICAL ISSUES • Positive urine culture for bacilli is typical • Remember, especially in children, absence of lower UTI does not exclude pyelonephritis DIAGNOSTIC CHECKLIST • Pyelonephritis usually asymmetric; sonographic changes may be subtle in acute setting • Focused US evaluation for ureteral stones if AP is suspected, including transvaginal images for distal ureter stones, because presence of stones would alter management (Left) Transverse US of the kidney exhibits a geographic area of increased echogenicity in the anterior interpolar region st in an area of focal pyelonephritis. (Right) Longitudinal US of the kidney illustrates diffuse loss of corticomedullary differentiation, crescentic perinephric fluid st, and urothelial thickening in a patient with acute pyelonephritis. (Left) Longitudinal US of the kidney illustrates a focal, wedge-shaped area of increased echogenicity st in a patient with pyelonephritis, (Right) Longitudinal color Doppler US of the same kidney shows a focal area of diminished color flow st corresponding to the hyperechoic wedge in an area of infection. 476

Acute Pyelonephritis<br />

Diagnoses: Urinary Tract<br />

IMAGING<br />

• Findings of acute pyelonephritis (AP) are almost always<br />

asymmetric<br />

• Renal enlargement with loss of corticomedullary (CM)<br />

differentiationon US <strong>and</strong> CT<br />

• Geographic areas of altered echogenicity on US<br />

• Urothelial thickening on US <strong>and</strong> CT<br />

• In general, ultrasound is much more sensitive for causes<br />

(obstruction) <strong>and</strong> complications (abscess) of AP than for AP<br />

itself, which is a clinical diagnosis<br />

• Many kidneys with pyelonephritis will be sonographically<br />

normal<br />

• Foci of gas in parenchyma (rare) could indicate<br />

emphysematous pyelonephritis; treat as urologic<br />

emergency<br />

• Altered nephrogram on CT, classically striated, best seen in<br />

excretory phase<br />

• Microabscesses or areas of necrosis can emerge after 1-2<br />

weeks of infection<br />

KEY FACTS<br />

PATHOLOGY<br />

• Most common organism: Escherichia coli<br />

• Route of spread of infection: Ascending (85%) ><br />

hematogenous (15%)<br />

• Risk factors include obstruction, ureteric reflux, diabetes,<br />

pregnancy, lower UTI<br />

CLINICAL ISSUES<br />

• Positive urine culture for bacilli is typical<br />

• Remember, especially in children, absence of lower UTI<br />

does not exclude pyelonephritis<br />

DIAGNOSTIC CHECKLIST<br />

• Pyelonephritis usually asymmetric; sonographic changes<br />

may be subtle in acute setting<br />

• Focused US evaluation for ureteral stones if AP is<br />

suspected, including transvaginal images for distal ureter<br />

stones, because presence of stones would alter<br />

management<br />

(Left) Transverse US of the<br />

kidney exhibits a geographic<br />

area of increased echogenicity<br />

in the anterior interpolar<br />

region st in an area of focal<br />

pyelonephritis. (Right)<br />

Longitudinal US of the kidney<br />

illustrates diffuse loss of<br />

corticomedullary<br />

differentiation, crescentic<br />

perinephric fluid st, <strong>and</strong><br />

urothelial thickening in a<br />

patient with acute<br />

pyelonephritis.<br />

(Left) Longitudinal US of the<br />

kidney illustrates a focal,<br />

wedge-shaped area of<br />

increased echogenicity st in a<br />

patient with pyelonephritis,<br />

(Right) Longitudinal color<br />

Doppler US of the same kidney<br />

shows a focal area of<br />

diminished color flow st<br />

corresponding to the<br />

hyperechoic wedge in an area<br />

of infection.<br />

476

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