Light and ultrastructural studies of renal oncocytic adenoma

Lectin staining of renal cell tumours with special emphasis on oncocytomas

There are conflicting results respecting the segmental tubular origin of renal oncocytomas, a type of tumour said to be highly differentiated and benign, though metastases have been described. The aim of this study was, by applying different lectins on renal cell carcinomas (n = 50) and oncocytomas (n = 12), to search for patterns which could indicate a specific segmental origin of oncocytomas and perhaps elucidate the differentiation of this tumour. The following lectins were applied: jacalin, peanut agglutinin (PNA), wheat germ agglutinin (WGA), phytohemagglutinin E (PHA-E), concanavalin A (Con A), and Dolichos biflorus agglutinin (DBA). The results show that oncocytomas are positive when jacalin, a Lectin that stains distal tubules and collecting tubules, is used, supporting the view that the tumour derives from distal or collecting tubules. The staining of the oncocytomas is generally polarized as in normal kidney tubules underlining that the tumour is highly differentiated. Two oncocytomas with aggressive behaviour showed areas with a diffuse pattern suggesting lower differentiation.

Renal cell carcinoma vs. renal oncocytoma. Report of a case with overlap features and review of the literature

Although the salient features of renal oncocytomas and renal cell carcinomas have been discussed in the recent literature, renal masses with features of both entities will present diagnostic difficulty, especially when the cells are diffusely eosinophilic on microscopic examination. A case of a firm, tan, rounded mass replacing the lower pole of the kidney is discussed. The final diagnosis of renal cell carcinoma, granular cell type, was made after multiple sections of the tumor were examined, and after electron microscopy was performed. A thorough search by light microscopy should be made for clear cell foci, necrosis, mitotic activity, and vascular or capsular invasion, features generally accepted as pathognomonic for renal cell carcinoma. Cellular and especially nuclear pleomorphism is typically focal or mild in renal oncocytomas. True oncocytic tumors will be packed with mitochondria on electron microscopy; however, granular renal cell carcinomas will contain mitochondria as well as other cellular organelles, lipid, and glycogen. Electron microscopy should be performed on tumors suspected of being oncocytomas because eosinophilia on hematoxylin and eosin stain, as demonstrated by this case, is not a predictable measure of mitochondria content. Immunoperoxidase staining for vimentin in oncocytomas has recently been shown to be negative, and may offer a method of ruling out oncocytoma in vimentin-positive tumors, pending further studies.

[Classification of renal cell carcinoma/tumors and their relationship to the nephron-collecting tubules system]

After a controversial phase of nomenclature (including--among others--the terms "hypernephroma" and "hypernephroid carcinoma") a cytomorphologically defined subtyping of renal cell tumours (adenomas, carcinomas, oncocytomas) is offered, based on new electron microscopical and histochemical observations. These data are in part supported by cytogenetical findings reported in the literature. Phenotypical/histogenetical relations to different parts or cell types, respectively, of the nephron-collecting duct system could be demonstrated. Chromophobe cell carcinoma and oncocytoma exhibit features of the intercalated cells.

Immunocytochemical demonstration of cytochrome c oxidase as a marker for renal oncocytes and oncocytomas

Using an antibody raised against the mitochondrial enzyme cytochrome c oxidase (EC 1.9.3.1), it was possible to visualize microoncocytomas, oncocytic tubules and even single oncocytes in the renal cortex of rats treated with N-nitrosomorpholine, and to localize the lesions to the collecting duct of the nephron. In human specimens, the antibody also stained oncocytomas and oncocytic tubules in the surrounding macroscopically unaffected cortex. Thus, this antibody may be used for detection as well as for investigation of the development of oncocytic lesions in various species.

Intercalated cells as a probable source for the development of renal oncocytoma

Renal oncocytoma is a distinct type of epithelial tumor said to arise from the collecting duct system. Here we show that in nine of ten oncocytomas the tumor cells expressed an analog of the erythrocyte anion exchanger band 3. In the normal kidney band 3 is confined to the basolateral surface of the majority of intercalated cells which comprise up to 50% of the cortical collecting duct epithelium. Carbonic anhydrase c is another protein abundant in intercalated cells, and this was also expressed in six of the ten oncocytomas investigated. Immunoreactivity specific for band 3 and carbonic anhydrase c was not detected in any of the 20 renal cell carcinomas examined. At favourable section planes direct transitions between normal collecting ducts and oncocytic tubules were observed. These findings suggest that oncocytomas may develop from intercalated cells of the collecting duct epithelium.

Histogenesis of renal cell carcinoma and renal oncocytoma. An immunohistochemical study

The histogenesis of renal cell carcinoma and oncocytoma is controversial. We compared immunohistochemical profiles of normal kidney, nine carcinomas, and six oncocytomas. Carcinomas and oncocytomas expressed the following antigens respectively: proximal tubule--Uro 3 (56 & 67%), alpha-1-antitrypsin (89 & 50%); proximal and distal tubule--Uro 10 (67 & 83%); distal tubule--B2-microglobulin (100 & 100%); distal/medullary tubule--epithelial membrane antigen (89 & 83%), neuron-specific enolase (78 & 100%), glandular cytokeratin (78 & 100%), epidermal keratin (67 & 67%); and medullary tubule--Uro 8 (89 & 83%). All tumors, except one oncocytoma, had at least one positive reaction for each antigen group. Oncocytomas predominantly stained for distal/medullary tubular antigens; none showed a predominance of proximal tubular antigens. Carcinomas also demonstrated largely distal/medullary tubule antigens; 44% showed prominence of proximal tubular antigens as well. Assignment of an exclusive proximal, distal or medullary tubule origin to renal neoplasms does not appear valid. Divergent histogenesis from a precursor stem cell is likely.

Renal oncocytoma: origin from the collecting duct

The histo- and cytogenesis of two cases of renal oncocytoma have been studied by cytomorphological and cytochemical methods. Transitions from collecting ducts into oncocytic tubules were observed at the light and electron microscopic levels. The fine structure of the oncocytes in tubules and tumors is described in detail. Cytochemically, the oncocytic tubules and oncocytomas share many characteristics with the distal nephron, especially the collecting ducts. A striking difference is the enhanced activity of succinic dehydrogenase which corresponds to the increase in the number of mitochondria in oncocytes. All the results suggest that renal oncocytoma originates from the collecting duct.

Unilateral renal oncocytoma: a case report

A case of unilateral renal oncocytoma is reported. Diagnosis, clinical features and management of the tumour are discussed in the light of international literature. The value of angionephrography in the diagnosis of the tumour and in the preoperative planning of surgical therapy is emphasized.

Renal oncocytoma

Up to date only five cases of renal oncocytomas have been reported in Japan. We describe two cases of renal oncocytomas. Case 1: A 63-year-old woman, who had no urological symptoms, was pointed out of a cystic mass in the left kidney by chance. A resected kidney had a cystic tumor, which was well encapsulated and measured 6 X 7 X 8 cm. The tumor was unilocular and thick-walled cyst filled with bloody fluid. Histologically, the tumor was composed of oncocytes with eosinophilic granular cytoplasms that were packed with mitochondria. Case 2: A 70-year-old women died of malignant lymphoma and an autopsy was performed. The tumor was found in the right kidney by chance and measured 1 cm in diameter. The cut-surface of the tumor was uniform and tan-brown in color. Histologically, the tumor was composed of cells same as Case 1. We discuss the incidence of this tumor and the morphological characteristics of our cases.

Renal oncocytoma with synchronous contralateral renal cell carcinoma

We report a case of simultaneous contralateral oncocytoma and renal cell carcinoma. The diagnosis and prognosis of renal oncocytoma are discussed, and the management of bilateral renal tumors is reviewed.

Renal oncocytoma followed for eighteen years without resection

The natural history of unresected renal oncocytomas is unknown. We report a renal oncocytoma which was mistakenly diagnosed as benign renal cyst and followed up for eighteen years. We are unable to find other oncocytomas without resection which were followed up. The apparent lack of change in size over eighteen years supports the concept of slow growth. Malignant histologic characteristics confirm the potential for malignant degeneration in what is generally considered to be a benign lesion.

Computed tomography of renal oncocytomas

A retrospective analysis of 5 renal oncocytomas studied with CT was performed. Oncocytomas appeared as rounded hypodense solid masses with sharp margination from the normal renal parenchyma. They showed uniform homogeneous enhancement on CT scans performed after drip infusion of urographic contrast. One oncocytoma studied with dynamic CT scanning demonstrated a stellate (spoke-wheel) pattern of enhancement. No evidence of involvement of adjacent renal parenchyma, perinephric fat, renal veins or regional lymph nodes was present at CT and the findings were confirmed at surgery. Although the differential diagnosis between renal oncocytoma and hypernephroma may not be possible, preoperative awareness of a potentially benign lesion may guide the surgeon to attempt renal preserving surgery instead of the customary nephrectomy.

Morphologic features of renal oncocytoma: a light and electron microscopic study

Five renal oncocytomas were studied by light and electron microscopy. Five glutaraldehyde-fixed blocks from each tumor were examined. Scarce short, blunt microvilli, plasmalemmal interdigitations, basement membrane protuberances, and round or oval mitochondrial profiles were found, suggesting that these neoplasms arise from the epithelium of the distal tubule. Morphologic criteria for the diagnosis of renal oncocytoma, including ultrastructural demonstration of cytoplasmic filling by mitochondria, are presented.

Minimal-change lesion nephrotic syndrome with renal oncocytoma

A renal mass was found in a 49-year-old man presenting with idiopathic nephrotic syndrome. The excised tumor was a well-encapsulated renal oncocytoma. Examination of the kidney revealed a minimal-change glomerular lesion and moderate arterionephrosclerosis. Nephrotic range proteinuria persisted through a postoperative course of prednisone therapy, but diminished and cleared within the subsequent two-year period. Renal function has remained stable and proteinuria has not recurred over a four-year follow-up. The clinical course suggests a previously unreported relationship between renal oncocytoma and minimal-change lesion nephrotic syndrome.

Renal oncocytoma--bilateral, multifocal

One hundred thirteen cases of "grade I renal oncocytoma" are reported from several centers. All centers report absence of associated metastatic disease. In the present review of 219 radical nephrectomy specimens, 11 renal oncocytomas were identified, an incidence of 5 per cent. No diagnostic angiographic features could be identified. Multifocal potential is exemplified by study of a bilateral case and 2 cases of 2 independent oncocytomas in the same kidney. The fine histologic criteria distinguishing oncocytoma from malignant renal tumors suggest that the oncocytomas may have the potential of malignant degeneration. The possible "premalignant classification" of oncocytomas and the lack of dependable diagnostic features radiographically force the management to be the same as for Stage I renal carcinoma. The prognostic information available after histologic definition of renal oncocytoma is valuable.

Bilateral renal oncocytomas: a case report

We report on a man with bilateral multiple renal oncocytomas who had enlarged kidneys, and presented with loin pain and gross hematuria. A provisional diagnosis of multiple renal oncocytomas was made after renal angiography demonstrated the characteristic appearance of this tumor. The diagnosis was confirmed with histology of an open renal biopsy specimen. This case is unique in that the lesions were multiple and bilateral. The patient had impaired renal function and, hence, the necessity for conservative management once the histological diagnosis had been established. Since in previously reported cases oncocytomas have been removed completely our case provides an opportunity to observe the natural history of the disease.

Renal oncocytoma. A clinicopathologic study

Seven cases of renal oncocytomas are described. Two cases were from recent surgical and autopsy material seen within a period of ten months. Four cases were reclassified as renal oncocytomas from a 20 year review of 63 renal cell carcinomas removed operatively. One case was identified from a nine year review of 31 renal cell carcinomas coded in our autopsy files. All patients were males; mean age was 69 years. The smallest tumor measuring 0.3 X 0.3 X 0.3 cm represents the smallest renal oncocytoma reported. The largest tumor weighed 2350 g. It is the largest renal oncocytoma so far reported in the literature. Two of the cases were found in polycystic kidneys. None of the seven patients presented with symptoms related to the tumors and the subsequent clinical course was benign in all cases. Differential diagnosis from renal cell carcinoma is discussed in terms of light and electron microscopic and radiologic aspects. The previously reported cases in the literature are reviewed.

Renal oncocytoma. A review of the literature and report of an unusual multicentric case

Renal oncocytoma is a rare tumour of the kidney composed exclusively of large polygonal cells with eosinophilic, granular cytoplasm. Ultrastructurally they are distinguished by the presence of large numbers of mitochondria and histochemically by abundant oxidative enzymes and adenosine triphosphate. Macroscopically these tumours are usually light brown in colour and commonly exhibit a dense central area of fibrous scarring, with fibrous trabeculae extending from this central zone in a stellate fashion. Renal oncocytomas are commoner in males than females (sex ratio 2:1) and although the age range at presentation is wide, there is a peak incidence in the seventh decade. The prognosis following surgical removal is excellent, despite the fact that many of these tumours are large. Invasion of the perirenal fat and the renal vein and metastatic spread to regional lymph nodes is documented, but death from metastatic disease is rare. The great majority of renal oncocytomas reported are solitary. We describe a multicentric renal oncocytoma, the sixth so far reported.

Renal oncocytoma

Several authors have recently drawn attention to renal oncocytoma, a neoplasm hitherto rarely recognized. Their reports suggest that renal oncocytomas are not uncommon and that they are benign and possess distinctive gross, microscopical, ultrastructural, and behavioral features. Most examples were discovered on re-examination of neoplasms previously classified as renal adenocarcinoma or adenoma. In a survey of renal neoplasms filed in our Department, we identified 8 cases; these are reported and the literature is reviewed.