IS case 500: Oncocytoma
Imaging Sciences URMC 2010
Publication Date: 2010-08-30
History
Patient is a 69-year-old male with right flank pain.
Findings
There is a complex mass in the upper pole of the right kidney. This mass has T1 hypointensity and heterogeneously hyperintense on T2. The mass enhances on post-contrast images.
Diagnosis
Discussion
Renal oncocytoma is an uncommon, benign tumor that originates in the epithelium of the proximal tubules. The incidence of oncocytoma is approximately 3-7% of all renal neoplasms. About 2-12% of oncocytomas are multifocal, and 4-14% are bilateral, males to females ratio is 2-3:1 and the prognosis after partial or complete nephrectomy is excellent. Although renal oncocytoma is often detected as an incidental renal mass in an asymptomatic adult, it must be differentiated from other renal tumors, particularly renal cell carcinoma.
CT findings:
* Well-defined, homogeneous mass, solid density mass * Isodense or slightly hyperdense to the kidney * Central hypodense suggestive of scar * Tumor appears less dense than renal parenchyma on nephrogenic phase * Absence of malignant features including invasion or infiltration of perinephric fat, collecting systems or vessels
MR findings:
* T1: Well defined homogeneous hypo- or isointense to the kidney * T2: Slightly hyperintense to the kidney, "spoke-wheel" pattern, tumor necrosis * T1 post contrast: Homogeneous enhancement, non-enhancing central stellate scar
* Well-defined, homogeneous, hypo-/isoechoic mass * Central scar usually echogenic with central radiating vessels
References
- Palmer WE, Chew FS. Renal oncocytoma. AJR Am J Roentgenol. 1991 Jun;156(6):1144. PMID: 2028856
- Kalva S, Sahani D. Oncocytoma, kidney. eMedicine. December 19, 2008. http://emedicine.medscape.com/article/379653-overview
- Farkas LM, Székely JG, Karátson A. Bilateral, multifocal renal oncocytomatosis with rapid progression leading to renal insufficiency. Nephrol Dial Transplant. 1999 Sep;14(9):2262-3. PMID: 10489253
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