Kidney tumor - cysts, children, adult benign

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Kidney tumor - cysts, children, adult benign

Benign (usually) adult tumors

Schwannoma

Reviewers: Mandolin Ziadie, M.D. (see Reviewers page)
Revised: 30 March 2012, last major update March 2012
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.

General
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● Rare, benign tumor of Schwann cells
● Also called a neurilemoma

Epidemiology
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● < 25 cases reported in kidney through 2008
● Mean age 47 years, range 18-84 years

Clinical features
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● Usually asymptomatic (Mod Pathol 2000;13:851)

Case reports
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● 55 year old woman (Prague Med Rep 2011;112:137)

Treatment
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● Resection is curative (Mod Pathol 2008;21:779)

Gross description
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● Renal pelvic or parenchymal tumor that is well-demarcated, yellow-tan, smooth and bulging
● Average size, 10 cm; range 4 to 16 cm

Gross images
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Yellow-tan lobulated intrarenal mass

Multinodular masses of yellow-tan tissue with central cysts or softening

Micro description
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● Well-circumscribed, primarily cellular subtype (predominantly Antoni A pattern) with myxoid and hypocellular areas (Antoni B)
● May have microcystic degenerative changes with nuclear atypia (ancient schwannoma features, Can J Urol 2009;16:4948), aggregates of foamy macrophages

Micro images
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Antoni A areas with fascicular growth pattern, thick walled blood vessel and scattered lymphocytes

Circumscribed and encapsulated, no infiltration

Antoni B area with hyalinized and dilated blood vessel

Aggregates of foamy macrophages

Various images and stains; strongly S100+

Positive stains
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● S100

Negative stains
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● Cytokeratin, CD57 / Leu7, smooth muscle actin, desmin, CD34 and HMB-45

Differential diagnosis
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● Angiomyolipoma: triphasic with blastema and epithelioid component
● Synovial sarcoma: spindle cells plus nuclear pleomorphism and nuclear atypia, infiltrative margins
● Sarcomatoid carcinoma: marked atypia and renal cell carcinoma usually present, infiltrative margins and keratin+
● Low grade malignant peripheral nerve sheath tumor: larger cell size, frequent mitotic figures, cytologic atypia, nuclear pleomorphism and necrosis
● Solitary fibrous tumor: CD34+

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

Ref Updated: 3/9/12

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