Metanephric adenoma

Clinical features

Most often seen in women in the fifth decade.

Macroscopic appearances

Tumours are well circumscribed. Small tumours are white; larger tumours may be haemorrhagic.

Histopathology

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

Immunohistochemistry

• Always EMA negative

Cytogenetics

Normal

Differential diagnosis

• 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.

Prognosis

There is a single report of lymph node metastasis².

References

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.

©SMUHT/PW Bishop