Oncocytomas are the most commonly resected benign renal lesion.

In evaluating renal masses, the most important question is whether or not the lesion requires some form of intervention such as surgical excision or biopsy. To answer this question the most important characteristic of any given lesion in the kidneys is its enhancement pattern [1]. In general, enhancement of greater than 20 Hounsfield units would place the lesion into the surgical category. Conversely, enhancement of less than 10 Hounsfield units is not considered significant enhancement. Lesions which demonstrate between 10 and 20 units of enhancement are considered indeterminate and require further evaluation.

Given our current criteria, approximately 13% of all renal masses which are surgically resected are determined to be pathologically benign. In a review of cases where the resected lesions measured less than 3 cm, the number of benign lesions increased to 25% [1]. Oncocytomas are the most commonly resected benign renal lesion.

Oncocytomas represent 5% of all adult primary renal epithelial neoplasms. They are thought to originate from type A intercalated cells in the cortical collecting duct, have a peak age of incidence in the seventh decade of life, and demonstrate a male predominance. They typically appear as a solitary, well-demarcated, and unencapsulated renal lesion. In larger lesions there is often a central, stellate scar. In rare cases these lesions can present bilaterally, in which cases there is usually an associated hereditary syndrome (i.e. Birt-Hogg-Dubé) [2].

On angiography, there is a so-called spoke-wheel pattern for the arterial blood supply [2].

Most importantly oncocytomas are indistinguishable from renal cell carcinoma on diagnostic imaging and as a result require surgical resection.

• Pathology of Renal Oncocytoma - [PubMed REF]

• Radiologic Evaluation of Renal Masses - [PubMed REF] [PubMed REF]

• Imaging of Pyelonephritis - [PubMed REF]

• Renal Biopsy - [PubMed REF]

• Hyperattenuating renal masses - [PubMed REF]