Tumours are well circumscribed. Small tumours are white; larger tumours may be haemorrhagic.
These are epithelial tumours composed of tubules and papillae forming "glomeruloid bodies". Cells are uniformly bland. Psammoma bodes may be present.
Metanephric adenofibroma is a variant which combined areas of metanephric adenoma with areas of fibrosis.
FNA cytology of metanephric adenoma resembles a papillary thyroid lesion
Always EMA negative
Papillary renal cell carcinoma, particularly the solid variant. Papillary carcinomas have more cytoplasm, more irregular nuclei and more prominent nucleoli. Critically, papillary carcinomas are positive for EMA.
Wilm's tumour, particularly the epithelial predominant variant. Wilm's tumours have larger cells with greater nuclear hyperchromasia and a higher mitotic rate.
There is a single report of lymph node metastasis2.
1Renshaw, A. A. (2002). "Subclassification of renal cell neoplasms: an update for the practising pathologist." Histopathology 41(4): 283-300.
2Renshaw, A. A., D. R. Freyer, et al. (2000). "Metastatic metanephric adenoma in a child." Am J Surg Pathol 24(4): 570-4.
This page last revised 5.1.2004.