New technique for nephron-sparing surgery in polar tumours. A modification of the Kim technique. / Nueva técnica para cirugía conservadora de nefronas en tumores polares. Una modificación de la técnica de Kim.

INTRODUCTION AND OBJECTIVES: Nephron-sparing surgery (NSS) is the indication, provided it is feasible and meets the international treatment guidelines. One of the objectives of performing NSS is to reduce the ischemia time as much as possible. We propose a surgical technique for treating polar renal tumours and those larger than 4cm based on the principle of the technique described by Kim in 1964. METHOD: The technique performs a continuous circular suture on the base of the tumour, achieving compression of the renal pole without vascular clamping, facilitating haemostasis and avoiding the blind transfixion performed in Kim's original technique. We selected 28 patients for the implementation of the technique. RESULTS: The patients' mean age was 56 years (30-69). The R.E.N.A.L. scores were as follows: 12 of low complexity, 12 of moderate complexity and 4 of high complexity. The mean surgical time was 109minutes (75-140), and the mean estimated blood loss was 120mL (50-300mL). No positive margins were identified, and no patients required blood transfusions. The mean stay was 3.7 days (2-6). There were no Clavien grade 2 or higher complications. There were 3 Clavien 1 complications (fever). The difference in glomerular filtration rate was -0.71mL/min/m2. The pathology was malignant in 26 cases, 19 of them clear-cell carcinomas. Two cases were reported as oncocytomas. CONCLUSION: The proposed technique showed acceptable results, with a low rate of complications in the patient group.

The cytologic category of oncocytic (Hurthle) cell neoplasm mostly includes low-risk lesions at histology: an institutional experience.

DESIGN: The cytological diagnosis of oncocytic/Hurthle cell neoplasms (OCN) represents a challenge with which cytopathologists face up to in their practice. The majority of these lesions undergo surgery for a definitive characterization of the nature mainly due to their more aggressive behavior than other malignant follicular lesions. In this study, we aimed at the evaluation of the effective malignant rate in a large cohort of OCNs. METHODS: From January 2008 to December 2011, we analyzed 150 cyto-histological OCNs and 64 benign oncocytic/Hurthle lesions (BOL). Both groups of patients were analyzed for clinical and cyto-histological parameters. All the nodules were sampled under sonographic guidance and processed with the liquid-based cytological method. RESULTS: In agreement with literature, we found a significant correlation only with female gender in both OCN (P=0.0160) and BOL groups. The 64 BOLs were histologically diagnosed as 15 Hashimoto thyroiditis (HT), 45 hyperplastic nodules in HT, and four papillary thyroid carcinomas (PTC, 6.2%). The 150 OCNs resulted in 141 (94%) oncocytic adenomas and nine (6%) malignant lesions. The latter group included five oncocytic carcinomas (OCC), three oncocytic variants of PTC, and one macrofollicular PTC featured by mild nuclear clearing with a dispersive cellular pattern. The malignant rate was respectively 6.2% in BOLs without any OCC whereas 3.3% OCC diagnosed in the OCN category. CONCLUSIONS: Our OCNs mostly resulted in histological adenomas with a lower rate of malignancy than in other series. Some morphological parameters (nuclear clearing, dysplasia, and dispersive cellular pattern) might be helpful in stratifying OCN patients into different risks of malignancy.

Telangiectatic oncocytoma: a previously undescribed variant of renal oncocytoma.

OBJECTIVES: To identify, describe, and investigate the clinical, radiologic, and pathologic features of 8 cases of telangiectatic oncocytoma. METHODS: Fifty-three consecutive renal oncocytomas were reviewed for the telangiectatic pathologic features that were subsequently correlated with the demographic, clinical, and radiographic findings. RESULTS: Telangiectatic oncocytoma accounted for 15% of the 53 renal oncocytomas collected in the past 7 years in our institution. On radiology, almost all presented as an enhancing mass and were suspicious for or consistent with a renal malignant tumor. Grossly, the tumors ranged from 2.4 to 6.0 cm (mean, 3.5 cm) and macroscopically were hemorrhagic spongy or multicystic masses without a central stellate scar. Microscopically, they were characterized by variably sized blood-distended spaces (<0.1-mm to 2- to 3-mm blood lakes) lined by typical oncocytoma cells and without evidence of degenerative changes. CONCLUSIONS: With its unique radiologic and pathologic presentations in comparison with classic renal oncocytoma, it is important to recognize this new variant of renal oncocytoma.

Occlusion angiography using intraoperative contrast-enhanced ultrasound scan (CEUS): a novel technique demonstrating segmental renal blood supply to assist zero-ischaemia robot-assisted partial nephrectomy.

BACKGROUND: Recent innovations in technology and operative techniques have enabled safe performance of robot-assisted zero-ischaemia partial nephrectomy (PN), thus preventing the deleterious effect of warm ischaemia time. OBJECTIVE: To describe a novel technique of occlusion angiography using intraoperative contrast-enhanced ultrasound scan (CEUS) for zero-ischaemia robot-assisted PN (RAPN). DESIGN, SETTING, AND PARTICIPANTS: We used a prospective cohort evaluation of five patients who had imaging suspicious of renal cell carcinoma (RCC) treated at a single centre. SURGICAL PROCEDURE: We used computed tomography with three-dimensional reconstruction to identify renal arterial anatomy and its relationship to the tumour. Then, RAPN was performed with selective clamping and demonstration of a nonperfused segment of kidney (occlusion angiography) using intraoperative CEUS. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: We prospectively collected data on baseline, perioperative, and postoperative parameters. RESULTS AND LIMITATIONS: We describe the effects seen on ultrasound contrast administration. Contrast flare is seen in the segment of the kidney that is perfused. When selective clamping is performed, a watershed (line of demarcation) between the perfused and nonperfused segments of the kidney is clearly seen, allowing excision of the tumour in a relatively avascular plane and ensuring an adequate oncologic margin, when feasible. The mean age was 68.2 yr of age (range: 36-85), and the mean tumour size was 29.6mm (range: 20-42). The mean intraparenchymal extension of the tumour was 22.6mm (range: 12-30). Three tumours were located on the right kidney and two on the left. The mean blood loss was 420ml (range: 200-1000). The histology revealed clear cell RCC in two patients, oncocytoma in two patients, and type 1 papillary RCC in one patient. All the surgical specimens had negative surgical margins. The mean decrease in glomerular filtration rate was 8.4ml (range: 0-24). The mean follow-up was 6.4 mo (range: 5-8), with no evidence of recurrence in any patient. The only limitation in adopting this technique is the need for an intraoperative ultrasound probe with a CEUS mode. However, most specialists who perform minimally invasive surgery for small renal tumours believe that intraoperative ultrasound scan imaging is essential to achieving adequate resection margins. CONCLUSIONS: Intraoperative CEUS can be a useful adjunct in determining whether zero-ischaemia RAPN is feasible by delineating the area of nonperfusion. This technique has several advantages over the currently available techniques, such as indigo carmine green and Doppler probes.

Spindle cell oncocytoma of the adenohypophysis with marked hypervascularity. Case report.

A 68-year-old male presented with a very rare case of spindle cell oncocytoma (SCO), a recently identified very rare neoplasm of the anterior pituitary, manifesting as panhypopituitarism and visual field defect. The pituitary tumor with suprasellar extension was only partially resected via transsphenoidal surgery because of the tumor consistency and bleeding. Histological diagnosis was consistent with schwannoma. The tumor regrew and angiography revealed hypervascularity, so a transcranial approach was employed for the re-operation which only achieved partial resection because of intraoperative extensive bleeding. The tumor cells showed similar histological and immunohistochemical profiles to the previous specimen, but electron microscopy demonstrated that cytoplasm abundantly filled with mitochondria. The final diagnosis of SCO was established and the patient received postoperative conventional radiation therapy of 50 Gy. Only 15 cases of SCO have been reported, and the diagnosis was mistaken in many cases as schwannoma, oncocytic pituitary adenoma, or craniopharyngioma, and multiple surgeries followed by radiation therapy were required.

[Correlation between pathologic features and perfusion CT of renal cancer: a feasibility study]. / Correlazione tra le caratteristiche anatomopatologiche e di TC con perfusione della neoplasia renale: studio di fattibilità.

OBJECTIVES: The computerized tomography with perfusion technique (pCT) has proved to have some potentialities in the oncologic field as a possible tool to identify neoangiogenesis in vivo. The purpose of the present job is to test the correlations existing between perfusion data and pathologic features in the evaluation of vascularization in kidney cancer. METHODS: 6 patients with clinical diagnosis of renal tumor awaiting surgical treatment underwent preoperatively pCT scans. Axial images encompassing the greatest diameter of the cancer were compared with the respective histological sections. RESULTS: A correlation between tumor histological subtype and perfusion index was observed and shown. Moreover, clear cell RCC of different Fuhrman grades showed statistically significant differences in perfusion values (T test). Specifically, high perfusion indexes were associated with high density of microvessels with abnormal architecture at the microscopic evaluation of tumor specimen. Conversely, lower perfusion index were detected in tumors with lower microvascular density. CONCLUSIONS: pCT scans can provide significant data on tumor angiogenesis and, eventually, suggest tumor histological subtype. The possibility of identifying preoperatively tumor histotype can be of particular relevance in patients with small renal tumors, suitable for minimally-invasive surgery or active surveillance program.

Fractal dimension of microvasculature in renal oncocytomas and chromophobe renal cell carcinomas.

The aim of this study was to evaluate and compare the microvascular architectural complexity in oncocytomas and chromophobe renal cell carcinomas (ChRCCs) by fractal box-counting on CD34-labeled slides. The study group consisted of 23 cases (12 oncocytomas and 11 ChRCCs) diagnosed from resections. Capillaries were highlighted by CD34, and digital images from randomly selected, non-overlapping areas were taken. Fractal dimensions of microvasculature were measured according to the "box-counting" method with the aid of image analysis software. Mean fractal dimensions (MFDs) were calculated and compared. Hierarchical cluster analysis was also performed to determine whether natural grouping occurs among the cases. Cluster analysis revealed that the cases tended to aggregate in two partially overlapping groups in which oncocytomas (8/12) and ChRCCs (7/11) predominate, respectively. A slight but statistically important difference was also revealed by the Mann-Whitney U test. Fractal dimension, a variable for measuring the geometrical complexity of highly irregular objects, is used for research in pathology. Although the number of cases is limited in our series, the results indicate an obscure but quantitatively measurable difference, which cannot be assessed by the naked eye. Similar studies investigating larger series are needed before a final conclusion can be made.

Microvascular network in renal carcinomas. Quantitative and tissue microarray immunohistochemical study.

The aim of the study was to investigate differences in microvessels between renal tumors. The material consisted of 97 clear cell carcinomas (CCRCC), 20 papillary carcinomas (PapRCC), 33 chromophobe carcinomas and 15 oncocytomas (RO). The endothelia were stained immunohistochemically for CD34 antigen. The vascular features were analyzed with the AnalySIS image processing system. The stains for VEGF, GLUT-1 and Ki67 were performed on tissue microarrays. The mean microvascular density (MVD) was 163.62 profiles/mm2 and microvascular area (MVA) was 3.75%. The highest values were seen in CCRCC and the lowest in PapRCC. The size and shape parameters of the individual vessels were also different between the tumors under consideration. The tumor diameter, MVD and MVA were inversely correlated, the relationship being the strongest for RO. The minimum spanning tree parameters were different between histological types, especially between CCRCC and PapRCC. The mean fractal dimension was 1.32, and similar in all cases. VEGF, Ki67 and GLUT-1 expression was the highest in CCRCC, and lowest in RO. The vascular parameters were correlated with Ki67, GLUT-1 VEGF expression, tumor grade, and inversely correlated with tumor diameter. The relationships in each tumor type were slightly different.

Hurthle cell neoplasms of the thyroid: sonographic appearance and histologic characteristics.

OBJECTIVE: The purpose of this study was to determine the sonographic features of Hürthle cell neoplasms (HCNs) of the thyroid. METHODS: We retrospectively analyzed the sonographic appearance of 15 histologically proven HCNs in 15 patients aged 16 to 70 years (mean age, 44 years). Sonographic features that were reviewed included the size and echogenicity of the tumors, the presence of cystic areas or calcifications, and detectable blood flow on color Doppler imaging. Correlation of sonographic findings with pathologic results was performed. RESULTS: The tumors ranged from 0.4 to 7 cm in diameter, but most were less than 3 cm in diameter. Four (27%) of the 15 tumors were homogeneously hypoechoic. Two tumors (13%) were predominantly hypoechoic with isoechoic areas to thyroid parenchyma. Two (13%) neoplasms were isoechoic to thyroid parenchyma. Four (27%) tumors were predominantly isoechoic, containing hypoechoic areas, and 3 (20%) tumors were hyperechoic. Three neoplasms contained cystic components. None of the tumors contained calcifications. One tumor was avascular on Doppler examination. One neoplasm showed only peripheral blood flow. Thirteen tumors showed internal vascularity, 7 of them with peripheral blood flow. Twelve HCNs were benign, and 3 were malignant on pathologic examination. CONCLUSIONS: Hürthle cell neoplasms show a spectrum of sonographic appearances from predominantly hypoechoic to hyperechoic lesions and from peripheral blood flow with no internal flow to extensively vascularized lesions. Pathologic criteria differentiating benign and malignant HCNs (absence or presence of a capsular breach, vascular or extrathyroidal tissue invasion, nodal involvement, and distant metastasis) are beyond the resolution of sonography and fine-needle aspiration biopsy and require removal of the entire lesion. This precludes diagnosis and characterization of HCNs by sonography.

Fine-needle aspiration biopsy of Hurthle cell lesions of the thyroid gland: A cytomorphologic study of 139 cases with statistical analysis.

BACKGROUND: Lesions of the thyroid gland composed of Hurthle cells encompass pathologic entities ranging from hyperplastic nodules with Hurthle cell metaplasia to Hurthle cell carcinomas. The cytologic distinction between these entities can be diagnostically challenging. Many cytologic features of Hurthle cell lesions that distinguish neoplastic Hurthle cell lesions requiring surgery from those that are benign and nonneoplastic have been described, but with variable usefulness. This is due, in part, to the small numbers of cases examined in previous studies and the limited application of statistical analysis. A morphologic study was made of 139 Hurthle cell lesions of the thyroid gland and statistical analysis applied to identify a set of cytomorphologic features that distinguish benign Hurthle cell lesions (BHCL) from Hurthle cell neoplasms (HCN). METHODS: Fine-needle aspiration biopsies (FNABs) of thyroid nodules with a predominant Hurthle cell component and corresponding histologic followup were included in the study. Cases were divided into BHCL and HCN groups on the basis of the histologic diagnosis. All cases were reviewed to assess the following 14 cytologic features: overall cellularity, cytoarchitecture, percentage of Hurthle cells, percentage of single cells, percentage of follicular cells observed as naked Hurthle cell nuclei, background colloid, chronic inflammation, cystic change, transgressing blood vessels (TBV), intracytoplasmic lumina, presence of multinucleated Hurthle cells, nuclear to cytoplasmic ratio, nuclear pleomorphism/atypia, and nucleolar prominence. The results were evaluated by using univariate and stepwise logistic regression (SLR) analysis; statistical significance was achieved at P-values < 0.05. RESULTS: One hundred thirty-nine FNAB specimens, corresponding to 56 HCN and 83 BHCL, fulfilled the study criteria. Six of the 14 cytologic features evaluated were shown by univariate analysis to be statistically significant in predicting HCN: nonmacrofollicular architecture (P < 0.001), absence of background colloid (P < 0.001), absence of chronic inflammation (P < 0.001), presence of TBV (P < 0.001), > 90% Hurthle cells (P < 0.001), and >10% single Hurthle cells (P = 0.014). The first four of these features were also shown to be statistically significant in the SLR analysis (P = 0.005, 0.010, 0.016, and 0.045, respectively), and when all four of these features were present HCN was correctly identified 86% of the time. CONCLUSIONS: In the current study of 139 FNAB specimens of thyroid Hurthle cell nodules, 14 cytologic features were examined and 6 were found to be statistically significant in identifying HCN. The following four features, when found in combination, were found to be highly predictive of HCN: nonmacrofollicular architecture, absence of colloid, absence of inflammation, and presence of TBV.

Computerized nuclear morphometry and quantitation of angiogenesis in thyroid neoplasms.

The aim of this study was to investigate the nuclear and angiogenetic profile in different types of thyroid neoplasms and to make any possible statistical comparison between the different nuclear morphometric and angiogenetic parameters, in order to search for new diagnostic and prognostic criteria. Sixty two cases of thyroid neoplasms were classified as follows: 31 papillary carcinomas, 10 follicular neoplasms (5 adenomas and 5 carcinomas), 5 undifferentiated carcinomas, 6 Huerthle-cell carcinomas and 10 medullary carcinomas. Using an image analysis system, six nuclear morphometric and eight angiogenetic variables were measured for each case. Concerning nuclear morphometric variables, statistical differences were found mainly between undifferentiated and overall subtypes of differentiated carcinomas, as well as between follicular adenomas and carcinomas. Concerning angiogenesis variables, statistical differences were found only in the vessel's minor axis length between undifferentiated and overall subtypes of differentiated carcinomas, between MVD of follicular adenomas and carcinomas respectively, as well as between MVD of medullary carcinoma and follicular cell carcinomas generally. In conclusion nuclear morphometry and quantitation of angiogenesis could offer two additional parameters in the distinction between follicular adenomas and carcinomas. However, they cannot serve as absolute diagnostic criteria since they are only based on statistical differences. From a prognostic point of view, nuclear morphometry may have some relevance as far as follicular-cell neoplasms are concerned since the more aggressive anaplastic carcinomas have a distinct morphometric profile. Moreover, our study revealed differences in the angiogenetic profile between medullary and follicular cell carcinomas.

Role of color flow Doppler sonography in pre-operative diagnostics of the thyroid pathology.

BACKGROUND: The aim of this work is to demonstrate the high effectiveness of preoperative diagnosis by echotomographic study of thyroid nodules through color-Doppler sonography integrated by B-mode. The authors performed both B-mode ultrasonography and color-Doppler sonography on 125 patients expecting total thyroidectomy surgical intervention, without a previous evaluation of a number of other already performed clinical and instrumental tests. After the intervention, we compared the histologic test with the data drawn from the ultrasound scan, in order to demonstrate that color-Doppler sonography is able to provide for additional diagnostic information in the preoperative period. METHODS: One hundred and twenty five patients with thyroid pathologies were examined by both B-mode and color-Doppler sonography. Two diagnoses were made for each clinical case: the first supported by B-mode data, the second based on vascularity. Our aim was to check color-Doppler's ability to provide new information in the ultrasound diagnosis. All patients underwent a total thyroidectomy surgical intervention. The data were examined by K concordance test. RESULTS: Ultrasound data were compared with the histologic test, which showed 118 (97.4%) benign and 7 (5.6%) malignant lesions. B-mode ultrasound test gave a correct diagnosis in 115 (97%) out of 118 benign lesions and in 4 (57%) out of 7 malignant lesions, while 3 (2.5%) out of 118 cases were false positive and 3 (42.8%) out of 7 were false negative. In those cases showing a wrong conventional ultrasound diagnosis, after the integration of B-mode with color-Doppler results, a decrease was recorded in both false negative and false positive. CONCLUSIONS: Even if no correspondence was found between the different aspects of blood flow and the histologic types of lesions, this experience proves that the color-Doppler test has a high predictive value of benignity in cases with pattern I II and IV, while lesions with pattern III should be more carefully examined, since both malignant and benign lesions belong to this group. From the data drawn from this study, we are able to infer that color-Doppler sonography is undoubtedly an advantage not only in terms of cutting the false negatives, but also in the aim of obtaining a higher effectiveness in the screening of goitrogenic pathology.

Giant renal oncocytoma.

We report the largest renal oncocytoma excised at the initial presentation and the second largest renal oncocytoma in published reports. Despite a tendency for renal oncocytomas to be relatively small and asymptomatic compared with renal cell carcinomas, these lesions cannot be reliably differentiated preoperatively. The variable nature of presentation and overlap of radiographic characteristics between these lesions complicates their clinical differentiation. The present case illustrates the difficulty in the preoperative diagnosis of even very large, enhancing renal masses and reinforces the inclusion of renal oncocytoma in the differential diagnosis of these lesions.

Double-phase helical CT of small renal parenchymal neoplasms: correlation with pathologic findings and tumor angiogenesis.

PURPOSE: To correlate the enhancement pattern of double-phase helical computed tomography (CT) of small renal parenchymal neoplasms with pathologic findings and tumor angiogenesis, and evaluate whether the enhancement pattern would be useful in differentiating the histomorphologic types of small renal parenchymal neoplasms. MATERIALS AND METHODS: Double-phase helical CT (5 mm slice) of the corticomedullary phase (CMP) and late nephrographic phase (NP) was performed in 40 surgically resected renal neoplasms <3.5 cm. The patterns of CT attenuation value and homogeneity were correlated with the subtypes of neoplasms, microvessel density, and the existence of intratumoral necrosis or hemorrhage. RESULTS: Clear cell renal cell carcinomas (RCC) (n = 29) showed a peak attenuation value in the CMP of >100 HU [Hounsfield units]. Chromophobe cell RCC (n = 2) showed a peak attenuation value in the CMP of <100 HU. Papillary RCC (n = 5) showed a gradual enhancement with the attenuation value in the CMP of <100 HU. However oncocytomas (n = 2) and metanephric adenomas (n = 2) also showed patterns similar to these subtypes of RCC. The degree of enhancement in the CMP correlated with microvessel density (r = 0.87). All tumors with an homogeneous enhancement pattern did not show necrosis or hemorrhage on histologic specimen. CONCLUSION: The enhancement pattern in double-phase helical CT was different among the subtypes of RCC, and correlated with microvessel density or the existence of intratumoral necrosis or hemorrhage. However it did not differentiate between RCC and other solid tumors.

[Value of invasive preoperative imaging in kidney tumors of malignant or uncertain character]. / Stellenwert der invasiven präoperativen Bildgebung bei Nierentumoren maligner oder unklarer Dignität.

Preoperative staging of malignant renal tumors or undetermined dignity is mainly performed noninvasively using CT or MRI. In cases with vascular invasion or a solitary kidney extensive invasive evaluation of the tumor can influence preoperative planning. We report two cases of oncocytoma and renal cell carcinoma with extensive imaging using DSA or helical CT-cavography.

Renal oncocytoma and chromophobe renal cell carcinoma. A comparison of colloidal iron staining and electron microscopy.

Chromophobe renal cell carcinoma (RCC) is characterized by diffuse cytoplasmic staining with Hale colloidal iron (HCI) and the presence of numerous microvesicles. The eosinophilic variant morphologically may resemble renal oncocytoma. The latter commonly shows focal cytoplasmic HCI reactivity, but microvesicles have not been previously reported. We examined 19 chromophobe RCCs and 28 oncocytomas for their HCI staining patterns. Electron microscopy was performed on 13 chromophobe RCCs and 10 oncocytomas. In all cases of chromophobe RCC, more than 75% of cells showed a diffuse cytoplasmic HCI positivity, whereas a variable proportion of cells in 20 oncocytomas showed focal cytoplasmic staining, in a perimembranous, apical, or perinuclear pattern. Ultrastructurally, chromophobe RCCs contained abundant microvesicles with varying numbers of mitochondria, whereas all oncocytomas contained abundant mitochondria with focal collections of microvesicles. The microvesicles, in perimembranous, apical, or perinuclear clusters or singly scattered throughout the cytoplasm, were morphologically indistinguishable from those in chromophobe RCCs. In most cases, the microvesicle location and HCI staining pattern correlated. Chromophobe RCC and oncocytoma have distinctive morphologic features that usually allow their recognition. In difficult cases, HCI staining and electron microscopy may help, but the presence of HCI positivity or microvesicles in an eosinophilic renal tumor does not rule out oncocytoma.

Small solid renal lesions: usefulness of power Doppler US.

PURPOSE: To evaluate whether the vascular pattern at power Doppler ultrasonography (US) improves diagnostic accuracy in small solid renal lesions over that at gray-scale US. MATERIALS AND METHODS: Gray-scale and power Doppler US were performed prospectively in 64 small (1.5-3.0-cm-diameter) solid renal lesions (26 renal cell carcinomas [RCCs], 34 angiomyolipomas, two oncocytomas, two pseudotumors). At gray-scale US, echogenicity and homogeneity of the lesion, an anechoic rim, intratumoral cysts, shadowing, or a central scar were sought. At power Doppler US, the vascular distribution was divided into four patterns. RESULTS: Findings at gray-scale US included an anechoic rim or intratumoral cysts in 20 of 26 RCCs (77%) and the two oncocytomas. Shadowing was seen in seven of 34 angiomyolipomas (21%). Echogenicity, homogeneity, and a central scar were not pathognomonic. At power Doppler US, pattern 3 (peripheral) or 4 (mixed penetrating and peripheral) was seen in all RCCs, seven of 34 angiomyolipomas, and the two oncocytomas. Pattern 1 (intratumoral focal) or 2 (penetrating) was seen in 27 angiomyolipomas. Pattern 1 or 2 was characteristic of angiomyolipoma. The rate of correct diagnosis was significantly increased with combined US (78%) as compared to that with gray-scale (42%) or power Doppler (45%) US alone. CONCLUSION: The vascular distribution at power Doppler US could add important information to gray-scale US findings for differential diagnosis of small solid renal lesions.

[Radiological diagnosis of renal oncocytoma].

Eight patients (nine tumors) with histologically proven renal oncocytoma are presented. In all cases, differential diagnosis between renal oncocytoma and renal cell carcinoma could not be done on ultrasonography. On selective renal angiography, extended arteries surrounding the tumor margin was demonstrated in six of seven tumors without a spoke-wheel arterial supply. A sharp and smooth margin with capsule (lucent rim) could be found in five cases, and a spoke-wheel configuration of vessels could be seen in only two cases. A spoke-wheel pattern might be found with tumor growth. All tumors on computed tomography (CT scan) have a distinct margin, a smooth contour and a homogeneous appearance on contrast enhanced CT scan. The capsule and the presence of a central scar were clearly seen on T1 and T2 weighted images of magnetic resonance imaging (MRI). It is helpful to differentiate the oncocytoma from renal cell carcinoma. The modality of MRI may be useful in the preoperative diagnosis of oncocytoma.