Diagnostic Ultrasound - Abdomen and Pelvis

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
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