Benign neoplasm composed of Metanephric tubular –like primitive cells
Mean age- 41 years
Range: 11 months- 83 years
range of age: 50-60 years-old
Most frequent in females
Clinical symptoms: flank pain, haematuria and polycythaemia
These tumours are part of a spectrum of tumours composed by different proportions of epithelium and mesenchymal/stromal tissue (metanephric adenoma, metanephric adenofibroma or metanephric stromal tumour).
The idea that some author’s advocate that this tumour may be related with papillary renal cell neoplasms is controversial (Pins M et al 1999).
Monomorphous small blue cell population in a clean background
Clusters, tubules papillae or rosettes
Numerous regular naked nuclei are usually present.
Round or oval nuclei show no atypia and a minimum amount of cytoplasm.
The chromatin is dense and regularly distributed and nucleolus is inconspicuous
No necrosis in the background and mitoses are seen.
Psammoma bodies can be seen in the center of tubular structure
Pax 8: positive
CD56: Negative( some cases of positivity reported)
BRAF mutation- 90%
Wilms tumour (epithelial predominant)
Patients are generally younger than 6 years-old
Extensive sampling might reveal other Wilms tumour components (blastema, mesenchyma)
Blastema is CD56 positive and CD57 negative
Wilms tubules are CD57 positive and CD56 negative -similar to immunoprofile of MA
No BRAF mutation
Solid variant of papillary (chromophil) RCC
cells are larger and show moderate amounts of cytoplasm
Macrophages are frequently present
CK7: Positive, diffuse and intense
EMA: Positive, diffuse and intense
WT1 : negative
trisomy 7 and 17 and sex chromosome loss
Most cases represent incidental findings.
Some cases, however may course with polycythaemia, abdominal pain or haematuria. S
Only recently two cases of metastasized metanephric adenomas were published.
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