Renal oncocytoma with and without intravascular extension into the branches of renal vein have the same morphological, immunohistochemical and genetic features

Abstract

We attempted to investigate the clinicopathological correlation of renal oncocytoma (RO) with renal vein extension. We identified seven ROs with extension into the branches of renal vein. The age of seven patients ranged from 61 to 82 years. Five cases were identified; incidentally, two patients had gross hematuria. After surgery, all patients were alive and free of tumors with follow-up of 1 to 5 years (mean=3.6). Oncocytomas measured from 2.2 to 7.5 cm. Renal vein extension was grossly suspected in 5/7 cases and histologically confirmed in all seven cases. Tumor cells were positive for cytokeratins, mitochondrial antigen, epithelial membrane antigen, and parvalbumin; 5/7 tumors were focally positive for cluster of differentiation 117. Ultrastructurally, the cytoplasm was packed by mitochondria. Molecular genetic analysis did not detect abnormal numbers of chromosomes 1, 2, 6, 7, 10, 17, and XY by fluorescence in situ hybridization, loss of heterozygosity on 3p, and mutation of Von Hippel-Lindau gene in all cases. Array comparative genomic hybridization analysis of two cases did not show any major genetic changes. Conclusions are: (1) renal oncocytomas may have intravascular extension to the branches of the renal vein; (2) renal oncocytomas with intravascular extension to the branches of the renal vein have the same morphological, immunohistochemical, and cytogenetic findings as have their counterparts without evidence of intravascular invasion; (3) the absence of metastases suggests an overall benign behavior of this tumor, but this has to be substantiated by further studies with a long-term follow-up; (4) in a renal tumor with granular cytoplasm showing renal vein extension, it is necessary to carefully exclude renal cell carcinomas (RCC) such as chromophobe RCC, oncocytic variant of papillary RCC, and granular variant of clear cell RCC.

Renal Oncocytoma and Cromophobe Renal Cell Carcinoma: Main Morphological Differences and Proposal of a Simple Histochemical and Immunohistochemical Panel to separate them

“…The diffuse pattern of growth is in our opinion the outstanding architectural factor for differentiate between RO an ChRCC, since most of our group of ChRCC possess it and was not found in any of the RO, agrees with published series [2,3]. Others topics don't possess the same diagnostic value like the presence of tumoral focuses on fatty perirrenal tissue or the vascular permeations, that reach around 10% and 5 % respectively in diverse series [2,3,18] and ranges highest in our series, don't reach statistical value in the differential diagnosis. Of the cytological characteristics, some wellknown elements are confirmed to differentiate both entities, which are the presence of typical or atypical mitosis and necrotic focuses [2,3], however their frequency is low, like you see in this series and in others, hence its usefulness is limited.…”

Sporadic hybrid oncocytic/chromophobe tumor of the kidney: a clinicopathologic, histomorphologic, immunohistochemical, ultrastructural, and molecular cytogenetic study of 14 cases

“…Some oncocytomas are composed of mixed population of cells with normal as well as abnormal karyotypes [16,17]. In a previous study, no numerical chromosomal changes were detected using comparative genomic hybridization in RO with renal vein extension [18]. However, loss of chromosomes 1 and 14 has been reported in RO [19,20].…”

Diagnostic criteria for oncocytic renal neoplasms: a survey of urologic pathologists

“…There was decreasing certainty for extension into structures as unequivocally compatible with an oncocytoma diagnosis, ranging from extension into perinephric fat [7-10] (59%) to involvement of renal sinus fat (53%) to invasion of the renal vein or a vein branch [7,11,12] (35%, Figure 4). …”

“…This decreased slightly to 53% for renal sinus fat involvement, which is well-known as an invasive pathway in clear cell renal cell carcinoma, [26] but has not been thoroughly studied in oncocytoma. A few studies have reported that vascular invasion, including renal vein invasion or renal vein branch invasion, does not necessarily alter the benign behavior of oncocytoma; [7,11,12] however, acceptance of this as compatible with oncocytoma decreased to 35%, with 41%…”