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 five of seven cases and histologically confirmed in all seven cases. Tumor cells were positive for cytokeratins, mitochondrial-antigen (MIA), epithelial membrane antigen (EMA), and parvalbumin; five of seven tumors were focally positive for CD117. 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. Our conclusions are as follows: (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; and (4) in a renal tumor with granular cytoplasm showing renal vein extension, it is necessary to carefully exclude renal cell carcinomas such as chromophobe RCC, oncocytic variant of papillary RCC, and granular variant of clear cell RCC.

Modern Pathologic Diagnosis of Renal Oncocytoma

“…It is also interesting that several reports have encountered vein or vein branch invasion in renal oncocytoma ( Figure 2D ), again noting that this does not appear to affect the benign behavior of oncocytoma ( 8 , 21 , 22 ). In renal cell carcinomas, extension into a vein or vein branch would warrant a pT3a pathologic stage category; however, vascular involvement by benign renal tumors, especially angiomyolipoma and rarely other entities, has also been reported ( 23 – 25 ).…”

Imaging of Solid Renal Masses

“…Patients with localized disease have 92% 5-year survival, while this decreases to 65% for those with regional metastasis, and 12% for patients with distant metastatic disease. 11 …”

“…8 Although oncocytomas are classified as benign tumors 9 , case reports have described malignant potential 10 . Similarly, aggressive local behavior may manifest with intravascular extension into branches of the renal vein 11 and invasion of the perinephric fat, the latter occurring in up to 7% of all oncocytomas 12 (figure 2). …”

Challenges in Pathologic Staging of Renal Cell Carcinoma

“…Therefore, these and other general questions were not counted in the denominator for consensus. On the basis of knowledge that tumor histologic subtypes have different growth patterns, including variable extension beyond the tumor pseudocapsule (more common in papillary renal cell carcinoma) 4 and that some benign neoplasms may have intravascular growth, [5][6][7] a set of questions also queried whether the participants believe that staging parameters may have different relevance based on tumor subtype.…”