Renal oncocytoma

Epidemiology

Oncocytomas constituted 3-5% of all renal tumours.

Macroscopic appearances

The tumour is the colour of the adjacent renal cortex. There may be a central scar. There is a diffuse form of renal oncocytosis³.

Histopathology

The architecture consists of small nests and tubules without broad trabeculae. The cells have granular cytoplasm. The nuclei lack atypia but there are small distinct nucleoli. The colloidal iron stain is negative or shows focal membrane positivity.

Immunohistochemistry

	Pancytokeratin KL-1	6/7 (diffuse positivity of more than 80% of tumour cells; 5, strong positivity of 50-80% of tumour cells; 1: study by tissue microarray)5
	34bE12	0/7 (study by tissue microarray)5
	Cam5.2	6/7 (diffuse positivity of more than 80% of tumour cells; 5, strong positivity of 50-80% of tumour cells; 1: study by tissue microarray)5
	CK7	3/62, 1/7 (heterologous positivity of less than 50% of tumour cells in one case : study by tissue microarray)5, 4/21 (four positive, seven focally positive)6 10/10 (patchy weak to moderate cytoplasmic staining wihtout membrane staining)7, 3/11 (weak staining of less than 5% of tumour cells)8, 3/69
	CK20	0/216
	EMA	4/62, 6/7 (diffuse positivity of more than 80% of tumour cells; 2, strong positivity of 50-80% of tumour cells; 1, heterologous positivity of less than 50% of tumour cells; 3: study by tissue microarray)5, 4/69
	MOC31	0/7 (study by tissue microarray)5
	BerEP4	2/7 (diffuse positivity of more than 80% of tumour cells; 1, heterologous positivity of less than 50% of tumour cells; 1: study by tissue microarray)5
	RCC Ma	1/7 (strong positivity of 50-80% of tumour cells; study by tissue microarray)5, 0/910, 0/12 (granular [eosinophilic] variants)14
	CD10	4/62, 0/7 (study by tissue microarray)53/910, 4/69, 7/12 (granular [eosinophilic] variants: 3 cases diffuse strong membrane or granular cytoplasmic positivity, 4 cases focal)14
	E-cadherin	5/7 (strong positivity of 50-80% of tumour cells; 5: study by tissue microarray)5
	CD15	4/7 (diffuse positivity of more than 80% of tumour cells; 1, strong positivity of 50-80% of tumour cells; 1, heterologous positivity of less than 50% of tumour cells; 2: study by tissue microarray)5
	CD117	12/12 (granular [eosinophilic] variants: diffuse strong membrane or granular cytoplasmic positivity)14
	RON	12/12 (granular [eosinophilic] variants: 9 cases diffuse strong membrane or granular cytoplasmic positivity, focal in 3 cases)14
	Vimentin	5/62, 0/7 (study by tissue microarray)5, 0/811, 0/812,1/69
	Parvalbumin	11/164, 8/811
	Antimitochondrial antibody	5/69
	b defensin-1	8/811
	Epcam	1/15 strongly membrane positive13
	Colloidal iron	5/12 (granular [eosinophilic] variants: focal faint apical and perinuclear cytoplasmic positivity)14

Differential diagnosis

• Chromophobe renal cell carcinoma, particularly the eosinophilic variant. Cells form broad trabeculae.Colloidal iron stain is positive. Some tumours show ares of oncocytoma and areas of chromophobe carcinoma: the correct classification of these is unclear.

Management

Observation or local resection.

Prognosis

There is a single case of metastasis to the liver².

References

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

² Perez-Ordonez, B., G. Hamed, et al. (1997). "Renal oncocytoma: a clinicopathologic study of 70 cases." Am J Surg Pathol 21(8): 871-83.

³ Tickoo, S. K., V. E. Reuter, et al. (1999). "Renal oncocytosis: a morphologic study of fourteen cases." Am J Surg Pathol 23(9): 1094-101.

⁴ Martignoni, G., M. Pea, et al. (2001). "Parvalbumin is constantly expressed in chromophobe renal carcinoma." Mod Pathol 14(8): 760-7.

⁵ Pan CC, Chen PC,Ho DM. The diagnostic utility of MOC31, BerEP4, RCC marker and CD10 in the classification of renal cell carcinoma and renal oncocytoma: an immunohistochemical analysis of 328 cases. Histopathology 2004; 45:452-9

⁶ Wu SL, Kothari P, Wheeler TM, et al. Cytokeratins 7 and 20 immunoreactivity in chromophobe renal cell carcinomas and renal oncocytomas. Mod Pathol 2002; 15:712-7

⁷ Mathers ME, Pollock AM, Marsh C, et al. Cytokeratin 7: a useful adjunct in the diagnosis of chromophobe renal cell carcinoma. Histopathology 2002; 40:563-7

⁸ Leroy, X., Moukassa, D., Copin, M.C., Saint, F., Mazeman, E. and Gosselin, B. Utility of cytokeratin 7 for distinguishing chromophobe renal cell carcinoma from renal oncocytoma. Eur Urol 2000;37:484-7.

⁹ Abrahams, N. A., G. T. Maclennan, et al. (2004). "Chromophobe renal cell carcinoma: a comparative study of histological, immunohistochemical and ultrastructural features using high throughput tissue microarray." Histopathology 45(6): 593-602.

¹⁰ Avery, A.K., Beckstead, J., Renshaw, A.A. and Corless, C.L. Use of antibodies to RCC and CD10 in the differential diagnosis of renal neoplasms. Am J Surg Pathol 2000;24:203-10.

¹¹ Young, A.N., de Oliveira Salles, P.G., Lim, S.D., Cohen, C., Petros, J.A., Marshall, F.F., Neish, A.S. and Amin, M.B. Beta defensin-1, parvalbumin, and vimentin: a panel of diagnostic immunohistochemical markers for renal tumors derived from gene expression profiling studies using cDNA microarrays. Am J Surg Pathol 2003;27:199-205.

¹² Morgan B et al. Immunohistochemical subtyping of renal cortical tumours. J Pathol July 2004, abstract 21.

¹³ Went P, Dirnhofer S, Salvisberg T, et al. Expression of epithelial cell adhesion molecule (EpCam) in renal epithelial tumors. Am J Surg Pathol 2005; 29:83-8

¹⁴ Wang HY,Mills SE. KIT and RCC are useful in distinguishing chromophobe renal cell carcinoma from the granular variant of clear cell renal cell carcinoma. Am J Surg Pathol 2005; 29:640-6

This page last revised 17.7.2005.

©SMUHT/PW Bishop