Metanephric adenoma and solid variant of papillary renal cell carcinoma: common and distinctive features

Histopathology. 2013 May;62(6):941-53. doi: 10.1111/his.12106. Epub 2013 Apr 3.


Aims: To evaluate morphological and immunohistochemical (IHC) features helpful in distinguishing metanephric adenoma (MA) from solid papillary renal cell carcinoma (s-PRCC).

Methods and results: We present a detailed study of 21 MA and 23 s-PRCC. The two entities exhibited significant similarities, both being well-circumscribed tumours composed of tightly packed small cells arranged in solid sheets or ill-defined tubules, often presenting glomeruloid bodies, psammoma bodies and dystrophic calcification, and showing overlapping immunoreactivity for S100, CD57 and CK7. Conversely, most MA were non-encapsulated, whereas most s-PRCC showed a thick fibrous pseudocapsule; MA cells had scanty cytoplasm and a high nuclear:cytoplasmic ratio in comparison to s-PRCC, where occasional tumour cells showed abundant cytoplasm and high nuclear grade. Polypoid branching fronds were common in MA, but absent in s-PRCC; multifocality and papillary hyperplasia/adenoma were seen only in s-PRCC. MA were positive for WT1 and negative for EMA and alpha-methylacyl-CoA racemase (AMACR); s-PRCC were positive for EMA and AMACR and negative for WT1.

Conclusions: Despite overlapping features, careful morphological and architectural evaluation should result in accurate diagnosis of most MA and s-PRCC. In challenging cases, IHC stains for WT1, EMA and AMACR may help in distinguishing these two entities.

MeSH terms

  • Adenoma / diagnosis
  • Adenoma / metabolism
  • Adenoma / pathology*
  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Biomarkers, Tumor / metabolism
  • CD57 Antigens / metabolism
  • Carcinoma, Renal Cell / diagnosis
  • Carcinoma, Renal Cell / metabolism
  • Carcinoma, Renal Cell / pathology*
  • Child
  • Child, Preschool
  • Diagnosis, Differential
  • Female
  • Humans
  • Immunohistochemistry
  • Keratin-7 / metabolism
  • Kidney Neoplasms / diagnosis
  • Kidney Neoplasms / metabolism
  • Kidney Neoplasms / pathology*
  • Male
  • Middle Aged
  • Mucin-1 / metabolism
  • Racemases and Epimerases / metabolism
  • S100 Proteins / metabolism
  • WT1 Proteins / metabolism
  • Young Adult


  • Biomarkers, Tumor
  • CD57 Antigens
  • KRT7 protein, human
  • Keratin-7
  • MUC1 protein, human
  • Mucin-1
  • S100 Proteins
  • WT1 Proteins
  • WT1 protein, human
  • Racemases and Epimerases
  • alpha-methylacyl-CoA racemase