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Kidney tumor - cysts, children, adult benign

Benign (usually) adult tumors

Juxtaglomerular cell tumor


Reviewers: Mandolin Ziadie, M.D. (see Reviewers page)
Revised: 4 December 2013, last major update January 2012
Copyright: (c) 2003-2013, PathologyOutlines.com, Inc.

General
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● Extremely rare (<100 cases) tumor that usually presents in young adults and originates from smooth muscle cells in the walls of the glomerular afferent arteriole (juxtaglomerular apparatus)

Epidemiology
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● Mean age 23-38 years<; some cases in children and in older adults
● Females > males

Clinical features
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● Associated with signs / symptoms of hyper-reninism including hypertension, hyperaldosteronism and hypokalemia
● Clinical differential includes other renin producing tumors including renal cell carcinoma, Wilms’ tumor, mesoblastic nephroma, hepatoblastoma, lung carcinoma, pancreatic adenocarcinoma, ovarian and soft tissue tumors, glioblastoma multiforme

Case reports
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● 10 year old boy with severe hypertension (Am J Surg Pathol 1994;18:837)
● 25 year old woman with high plasma renin activity (Arch Pathol Lab Med 1993;117:1161)
● 27 year old woman (Arch Pathol Lab Med 2004;128:e112)
● 46 year old man with 15 cm tumor that invaded renal vein and metastasized to both lungs (Am J Surg Pathol 2004;28:1098)
● 52 year old man with metastatic tumor (Am J Surg Pathol 2004;28:1098)
● 2 cases with a dominant papillary pattern (Hum Pathol 1993;24:1168)

Treatment
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● Nephron-sparing surgery is curative
● Blood pressure may normalize after excision (J Hypertens 2008;26:368)
● Usually benign behavior with no / rare recurrences or metastases (Am J Clin Pathol 2001;116:854)

Gross description
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● Well circumscribed, encapsulated, solitary with gray-white-yellow solid cut surface (may have focal hemorrhage / small cysts)
● Average 2-3 cm but may be 8 cm
● Usually doesn’t invade beyond kidney

Micro images
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Tumor at hilum

Micro description
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● Variable; usually sheets of homogenous round cells with granular eosinophilic or clear cytoplasm and distinct cell borders
● Other patterns are sheets / cords of spindle cells with irregular borders, papillary structures lined by flat or cuboidal cells with inner polygonal cells and tubules
● Numerous capillaries with hemangiopericytoma-like growth pattern
● Stroma may be scanty or abundant, composed of hyalinized or myxoid tissue
● Focal hemorrhage, mast cells and lymphoplasmacytic inflammation
● Rare / few mitoses, necrosis or pleomorphism

Micro images
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Sheets of cells with hemangiopericytoma-like vascular pattern


Organoid pattern

   

Round or oval cells with abundant cytoplasm and vesicular nuclei and chronic inflammatory cells


Epithelial cells with prominent granular cytoplasm


Trabecular growth of uniform epithelioid cells in hemangiopericytoma-like vascular network


Cells have granular cytoplasm and only mild pleomorphism

           
Various images


Various images


Renin granules are PAS+ diastase resistant


27 year old woman: figure 1: 2 cm, solid, tan cortical mass; fig 2: solid, compact pattern of round / polygonal cells with focal papillary and tubular patterns; fig 3: cells have moderate cytoplasm, round central nuclei, little stroma present; fig 4: EM shows rhomboid, membrane bound renin protogranules with 6-10 nm periodic crystalline array, some with an electron dense zigzag pattern traversing the array

Positive stains
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● PAS (cytoplasmic granules), vimentin, renin (strong and diffuse), renin RNA by ISH, SMA, CD34 and CD117 (Arch Pathol Lab Med 2006;130:707)
● actin (variable)

Negative stains
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● Cytokeratin, HMB45

Electron microscopy description
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● Membrane-bound rhomboid-shaped renin protogranules, secretory granules

Electron microscopy images
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Rhomboid-shaped renin protogranules

Molecular description
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● -9 and -11 (Hum Pathol 2008;39:459)

Differential diagnosis
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Metanephric adenoma: no papillary structures, no atypia, negative for PAS and renin
Papillary renal cell carcinoma: marked atypia, foam cells, negative for PAS and renin

End of Kidney tumor - cysts, children, adult benign > Benign (usually) adult tumors > Juxtaglomerular cell tumor


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