Kidney tumor - cysts, children, adult benign

Home Chapter Home Jobs Conferences Fellowships Books

Kidney tumor - cysts, children, adult benign

Childhood neoplasms

Metanephric stromal tumor

Reviewers: Mandolin Ziadie, M.D. (see Reviewers page)
Revised: 30 December 2011, last major update December 2011
Copyright: (c) 2003-2011, PathologyOutlines.com, Inc.

General
=========================================================================

● Benign spindle cell neoplasm of pediatric kidney composed of bland spindled cells that entrap native kidney
● Similar to and often misdiagnosed as mesoblastic nephroma
● May be related to Wilms’ tumor (Clin Lab Med 2005;25:379)

Epidemiology
=========================================================================

● Usually occurs in children with a mean age of 2 years (Am J Surg Pathol 2000;24:917)

Treatment
=========================================================================

● Excision is curative

Gross description
=========================================================================

● Fibrous lesion centered in renal medulla containing smooth walled cysts; mean 5.5 cm

Micro description
=========================================================================

● Nodular low power appearance
● Identical to stromal component of metanephric adenofibroma
● Bland spindle cells with thin, tapered and hyperchromatic nuclei and indistinct cytoplasm (may have epithelioid areas) that entrap native kidney, usually undermine calyceal or pelvic urothelium and may entrap nerves
● Non-encapsulated with a scalloped border with renal cortex
● Hypo- and hypercellular areas with onion-skin cuffing around entrapped renal tubules
● Stroma may show glial, cartilaginous or neuroblastic differentiation
● Angiodysplasia of entrapped arterioles
● May show juxtaglomerular cell hyperplasia in entrapped glomeruli
● No vascular invasion, no mitotic figures

Virtual slides
=========================================================================

Metanephric stromal tumor

Positive stains
=========================================================================

● Vimentin, CD34 (often patchy) and S100 (variable)

Negative stains
=========================================================================

● Smooth muscle actin, muscle specific actin, desmin, keratin and EMA (but entrapped tubules are positive), CD117 / c-kit and low Ki-67 index

Differential diagnosis
=========================================================================

● Clear cell sarcoma: regular branching capillary vascular pattern, no heterologous differentiation, CD34-
● Mesoblastic nephroma: classic variant has whorls and fascicles, metaplastic and dysplastic elements common, actin+, desmin+, CD34-
● Metanephric adenofibroma: neoplastic epithelium, no entrapped tubules

End of Kidney tumor - cysts, children, adult benign > Childhood neoplasms > Metanephric stromal tumor

This information is intended for physicians and related personnel, who understand that medical information is often imperfect, and must be interpreted in the context of a patient's clinical data using reasonable medical judgment. This website should not be used as a substitute for the advice of a licensed physician.

All information on this website is protected by copyright of PathologyOutlines.com, Inc. Information from third parties may also be protected by copyright. Please contact us at copyrightPathOut@gmail.com with any questions (click here for other contact information).