Renal cortical adenoma, papillary adenoma

Definition

These tumours are identical to low-grade papillary renal cell carcinoma but are less than 5 mm in diameter.

Epidemiology

These are very common incidental findings. They are found more commonly in kidneys containing renal cell carcinoma or oncocytoma, particularly the hereditary form of papillary renal cell carcinoma.

Macroscopic appearances

By definition, less than 5 mm in diameter, and usually less than 2 mm.

Histopathology

The tumour must histologically resemble papillary renal cell carcinoma.

Immunohistochemistry

Identical to papillary renal cell carcinoma.

	papillary renal cell adenoma
AE1/3
Cam5.2
HMW-CK
34bE12
CK7	7/72
CK19	4/52
CK20
CEA
EMA
dolichos biflorus agglutinin	5/72
CD10
CD117
renal cell carcinoma marker
b defensin-1
parvalbumin
vimentin
MIB-1
anti-mitochondrial antibody

Differential diagnosis

Small tumours that do not resemble papillary renal cell carcinoma are not adenomas: most are clear cell carcinomas.

Prognosis

Metastases have occurred with very small papillary primaries, but the prognosis is generally excellent.

References

1Renshaw, A. A. (2002). "Subclassification of renal cell neoplasms: an update for the practising pathologist." Histopathology 41(4): 283-300.

2Ono, Y., Ito, T., Tsujino, S., Aizawa, S. and Suzuki, M. [A study of papillary renal cell carcinoma. Clinicopathological, immunohistochemical features and its typing]. Nippon Hinyokika Gakkai Zasshi 1997;88:587-95.

This page last revised 11.1.2005.