Kidney tumor - cysts, children, adult benign

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Kidney tumor - cysts, children, adult benign

Childhood neoplasms

Anaplastic sarcoma

Reviewers: Mandolin Ziadie, M.D. (see Reviewers page)
Revised: 30 March 2012, last major update December 2011
Copyright: (c) 2003-2011, PathologyOutlines.com, Inc.

General
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● Rare tumor, first described in 2007 (Am J Surg Pathol 2007;31:1459)
● Characterized by a proliferation of anaplastic spindle cells with bizarre, pleomorphic nuclei and atypical mitotic figures
● May show chondroid differentiation

Epidemiology
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● Age range 1–41 years (median: 5 years; mean: 12 years) with slight female predominance

Case reports
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● 12 year old girl with chromosomal abnormalities in tumor (Hum Pathol 2010;41:1495)
● 24 year old woman (ScientificWorldJournal 2009;9:97)

Clinical features
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● Presents with a renal mass at an advanced stage
● Metastases to liver, lung and bone

Gross description
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● Large (mean: 12 cm) tumors, usually with cystic component
● Almost half involve pelvi-calyceal system

Micro description
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● Fascicular pattern of spindle cells with anaplastic changes diffusely or in multiple foci (bizarre pleomorphic cells and atypical mitotic figures)
● Foci of chondroid differentiation with both benign and malignant features, including islands of hyaline cartilage or chondroid matrix
● Occasional foci of osteoid and primitive blastema-like areas
● No epithelial structures, no nephrogenic rests

Micro images
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Spindle cells in collagenous stroma, also anaplastic cells in cellular focus

Positive stains
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● Vimentin, desmin and often p53

Negative stains
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● CAM 5.2, MyoD1, CD34, CD99 and WT1

Molecular description
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● Absence of synovial sarcoma t(X;18) and mesoblastic nephroma’s t(12;15) ETV6-NTRK3 translocation

Differential diagnosis
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● Anaplastic Wilms’ tumor: prominent blastema component, foci of epithelial differentiation, occasionally nephrogenic rests and no very atypical and wildly anaplastic cells in stroma and cartilage; blastema areas are WT1+ and CD56+
● Sarcomatoid carcinoma: has keratin+ epithelial component
● Primary renal synovial sarcoma: lacks t(X;18)

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