You are here: Urology Textbook > Kidneys > Renal metastases

Oncocytoma of the Kidney: Diagnosis and Therapy

Definition of Oncocytoma

Oncocytoma is a benign kidney tumor.

Epidemiology

3–7% of all kidney tumors.

Pathology of Oncocytoma

Gross pathology:

Homogeneous brown kidney tumor, often with a central scar.

Microscopic pathology:

Oncocytoma is characterized by polygonal eosinophilic cells arranged in clusters. The cells are rich in mitochondria, the cell nuclei are partly pleomorphic. The assignment of tumors with nuclear atypia to oncocytoma or renal cell carcinoma is challenging.

Diagnostic Workup of Oncocytoma

A preoperative distinction between oncocytoma and renal cell carcinoma is not possible with certainty; most authors recommend partial nephrectomy and pathological examination of the tumor.

Ultrasound of Oncocytoma:

With ultrasound imaging, an oncocytoma is indistinguishable from a renal cell carcinoma [fig. ultrasound imaging].

Computed Tomography:

Oncocytomas present in CT scan as contrast medium enriching renal tumors with mostly 4–6 cm in size [fig. CT imaging of an oncocytoma]. A central star-shaped scar is sometimes visible, but the differentiation to renal cell carcinoma is difficult (Choudhary et al., 2009).

MRI:

Oncocytomas present in MRI comparable to CT with a clearly visible capsule and a central stellate scar.

Renal Biopsy:

Renal biopsy is possible, but it is challenging to distinguish oncocytomas from renal cell cancer (e.g., eosinophilic variants) and to exclude the coexistence of RCC and oncocytomas.

Treatment of Renal Oncocytoma

If an oncocytoma is suspected, an organ-preserving approach (partial nephrectomy) should be pursued [fig. intraoperative finding of an oncocytoma].

References

Choudhary, S.; Rajesh, A.; Mayer, N. J.; Mulcahy, K. A. & Haroon, A. Renal oncocytoma: CT features cannot reliably distinguish oncocytoma from other renal neoplasms.
Clin Radiol, 2009, 64, 517-522

  Deutsche Version: Onkozytom der Nieren