Imaging spectrum of renal oncocytomas: a pictorial review with pathologic correlation

Insights into Imaging, Dec 2014

Objectives The purpose of this pictorial review is to present the imaging spectrum of renal oncocytomas with radiological-pathological correlation. Conclusion The differences in tumour cellularity (high cellularity or low cellularity with abundant stroma) and haemorrhagic/cystic change contribute to a wide spectrum of imaging findings of renal oncocytomas. Imaging findings substantially overlap those of common subtypes of clear cell and non-clear cell renal cell carcinomas. Multifocal renal oncocytomas are not rare, and making the diagnosis of oncocytoma with concomitant renal cell carcinoma is difficult. In addition, renal oncocytomas that demonstrate interval growth or develop in the setting of end-stage renal disease may be mistaken for malignancy. Teaching Points • High cellular components demonstrate avid arterial enhancement and subsequent washout. • Low cellular components demonstrate gradual subsequent enhancement owing to abundant stroma. • Cystic and hemorrhagic changes may account for lesion heterogeneity in the delayed phase. • Multifocal oncocytomas and oncocytomas coexisting with renal cell carcinoma are not rare. • Renal oncocytomas may demonstrate interval growth.

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Imaging spectrum of renal oncocytomas: a pictorial review with pathologic correlation

Kousei Ishigami 0 Aaron R. Jones 0 Laila Dahmoush 0 Leandro V. Leite 0 Marius G. Pakalniskis 0 Thomas J. Barloon 0 0 L. Dahmoush Department of Pathology, University of Iowa Hospitals and Clinics , Iowa City, IA , USA Objectives The purpose of this pictorial review is to present the imaging spectrum of renal oncocytomas with radiologicalpathological correlation. Conclusion The differences in tumour cellularity (high cellularity or low cellularity with abundant stroma) and haemorrhagic/cystic change contribute to a wide spectrum of imaging findings of renal oncocytomas. Imaging findings substantially overlap those of common subtypes of clear cell and non-clear cell renal cell carcinomas. Multifocal renal oncocytomas are not rare, and making the diagnosis of oncocytoma with concomitant renal cell carcinoma is difficult. In addition, renal oncocytomas that demonstrate interval growth or develop in the setting of end-stage renal disease may be mistaken for malignancy. Teaching Points High cellular components demonstrate avid arterial enhancement and subsequent washout. Low cellular components demonstrate gradual subsequent enhancement owing to abundant stroma. Cystic and hemorrhagic changes may account for lesion heterogeneity in the delayed phase. Multifocal oncocytomas and oncocytomas coexisting with renal cell carcinoma are not rare. Renal oncocytomas may demonstrate interval growth. - Renal oncocytoma is a benign renal tumour, accounting for approximately 37 % of all renal tumours [1]. Typical imaging findings of renal oncocytoma are described as a homogeneous hypervascular mass with subsequent washout in the delayed phase [2, 3] (Fig. 1). A central scar is a characteristic finding, especially in a large oncocytoma [4]. However, such classic imaging findings are not common [5]. In many cases, renal oncocytomas are surgically resected because preoperative imaging diagnosis is not reliable to distinguish oncocytoma from renal cell carcinoma (RCC). Kim et al. [6] found that segmental enhancement inversion based on the corticomedullary and early excretory phase was a characteristic enhancement pattern of oncocytoma (Fig. 2). Segmental enhancement inversion is a term defined as a renal lesion that has two distinct zones of enhancement which show inverse patterns between the corticomedullary (3040 s) and early excretory (120180 s) phases. One zone is hyperenhancing on the corticomedullary phase, which subsequently becomes hypo-enhancing on the early excretory phase. The other zone is hypo-enhancing on the corticomedullary phase and becomes hyper-enhancing on the early excretory phase [6, 7]. However, other studies have found it controversial whether or not segmental enhancement inversion is characteristic for oncocytoma [710]. Additionally, several studies examining the discrimination of RCC from oncocytoma based on the corticomedullary phase have shown inconsistent results [2, 1113]. Therefore, renal oncocytomas demonstrate various imaging findings. Not only may the discrimination of oncocytoma from RCC be challenging, but also the presence of Fig. 1 A 71-year-old man with classic renal oncocytoma in the left kidney. a The corticomedullary phase of the axial T1-weighted gradient echo (GRE) magnetic resonance (MR) image with fat saturation demonstrates an arterially enhancing mass (arrow) with hypointense central scar (small arrow). b The nephrographic phase demonstrates washout with enhancing central scar. c The axial T2-weighted fast spin echo (FSE) image with fat saturation shows the tumour to be of moderate signal (arrow) with hyperintense central scar (small arrow). d (High magnification) Oncocytoma, organoid pattern, tightly packed nests of tumour cells (T) with visible capillaries in the stroma (arrow) oncocytoma with concurrent RCC may be a diagnostic problem. Although imaging findings may not reliably discriminate oncocytoma from RCC, it is meaningful for radiologists to understand the wide imaging spectrum of oncocytomas when approaching the differential diagnosis of renal tumours. The purpose of this pictorial review is to present the imaging spectrum of renal oncocytomas. To aid in understanding the imaging findings of oncocytomas, radiologicalpathological correlations are provided. The diagnostic difficulties of discriminating renal oncocytoma from renal cell carcinoma Several studies examining the discrimination of clear cell RCC from oncocytoma based on arterial enhancement have revealed inconsistent results. For example, Gakis et al. [2] and Bird et al. [11] described that oncocytomas demonstrated g r e a t e r e n h a n c e m e n t t h a n c l e a r c e l l R C C i n t h e corticomedullary phase. On the other hand, Young et al. [12] described that clear cell RCC demonstrated greater enhancement than oncocytoma. Pierorazio et al. [13] described that peak enhancement of clear cell RCC was seen predominantly in the corticomedullary phase, while that of oncocytoma was seen predominantly in the (...truncated)


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Kousei Ishigami, Aaron R. Jones, Laila Dahmoush, Leandro V. Leite, Marius G. Pakalniskis, Thomas J. Barloon. Imaging spectrum of renal oncocytomas: a pictorial review with pathologic correlation, Insights into Imaging, 2015, pp. 53-64, Volume 6, Issue 1, DOI: 10.1007/s13244-014-0373-x