Adénome oncocytaire du rein : redéfinition des critères diagnostiques en tomodensitométrie

Feasibility of nephron-sparing surgery in giant oncocytoma

Oncocytomas represent 3 to 7% of renal masses and behave as benign tumours. Nephron-sparing procedures are preferred for biopsy confirmed lesions; however, giant oncocytomas have been generally treated by radical nephrectomy. We report the first case of partial nephrectomy in a 45-year-old man who presented with a 20-cm oncocytoma. At the 1 year follow-up, he had a normal functioning kidney. Despite the difficulty of this procedure, partial nephrectomy for very large benign tumours can be considered in appropriately selected young patients.

Comparison of segmental enhancement inversion on biphasic MDCT between small renal oncocytomas and chromophobe renal cell carcinomas

OBJECTIVE

The purpose of this article is to assess the usefulness of segmental enhancement inversion on biphasic MDCT in differentiating small (<4 cm) renal oncocytomas from chromophobe renal cell carcinomas (CRCCs).

MATERIALS AND METHODS

Eighty-two patients (40 men and 42 women) with a mean (±SD) age of 54±12 years (range, 21-75 years) with 27 renal oncocytomas and 55 CRCCs diagnosed by surgery who underwent contrast-enhanced biphasic CT between January 2000 and December 2011 were included. CT scans were interpreted by two radiologists who were blinded to the pathologic findings. The tumors were evaluated for size and segmental enhancement inversion. After independent evaluation, a consensus was reached by measuring the attenuation. Pathologic analysis determined the presence of fibrous septa, cystic change, hemorrhage, and necrosis. The Fisher exact test was used to evaluate the relationship between segmental enhancement inversion, tumor type, and specific pathologic changes. Interobserver concordance was evaluated with kappa statistics.

RESULTS

There were no significant differences in size between renal oncocytomas and CRCCs (p=0.458). Segmental enhancement inversion was present in 23, 20, and 21 (25.6%) of the 82 tumors according to reader 1, reader 2, and the consensus, respectively. The agreement was almost perfect (κ=0.843; p<0.001). Segmental enhancement inversion was more common in renal oncocytomas (63% [17/27]) than in CRCCs (7.3% [4/55]; p<0.001). There were no significant relationships between the four pathologic changes and tumor type or segmental enhancement inversion (p=0.351 and p=0.126, respectively).

CONCLUSION

Our study findings suggest that segmental enhancement inversion on biphasic MDCT may be useful in differentiating small renal oncocytomas from CRCCs.

Segmental enhancement inversion of small renal oncocytoma: differences in prevalence according to tumor size

OBJECTIVE

The purpose of this study was to retrospectively assess the prevalence of segmental enhancement inversion of small renal oncocytomas according to tumor size.

MATERIALS AND METHODS

Thirty-three patients (19 men, 14 women; mean age, 61 years; range, 40-74 years) with 33 oncocytomas diagnosed at surgical resection who had undergone contrast-enhanced biphasic CT between January 2000 and December 2011 were included. CT scans were analyzed by two radiologists blinded to the specifics of the pathology report for size, presence of segmental enhancement inversion, enhancement pattern, and homogeneity. Segmental enhancement inversion was present when a renal mass was divided into two differently enhanced segments in the corticomedullary phase (30-40 seconds after contrast injection) with the degree of enhancement reversed in the nephrographic phase (120-180 seconds after contrast injection). The masses were further assessed for fibrous septa, cystic change, hemorrhage, and necrosis. For statistical analysis, the Pearson chi-square test and linear regression were used to evaluate the relation between the prevalence of segmental enhancement inversion and tumor size or pathologic changes.

RESULTS

The mean diameter of 33 renal oncocytomas was 2.65 cm (range, 0.8-4.8 cm). There was no significant linear trend according to size (p = 0.762), although segmental enhancement inversion was significantly (p = 0.006) more common (10/12) in tumors measuring 1.5-2.9 cm. Pathologic change was present in 14 oncocytomas. There was no significant linear trend according to size (p = 0.068), but 2.5-cm and larger tumors had a significantly higher prevalence (57.9%) (p = 0.036). Segmental enhancement inversion was more common (13/19) in tumors without pathologic change (p = 0.024).

CONCLUSION

Segmental enhancement inversion was a characteristic finding in our series of small renal oncocytomas and was more common in tumors measuring 1.5-2.9 cm. Pathologic changes such as central scar were more common in oncocytomas larger than 2.5 cm and may be related to the low occurrence of segmental enhancement inversion.

How to characterise a solid renal mass: a new classification proposal for a simplified approach

The reference method for characterising a solid renal mass is computed tomography. MRI and ultrasound can provide useful diagnostic information for characterising masses the cystic or solid nature of which it is not possible to determine from data from the CT scan. For characterising a solid mass, only MRI can replace the CT scan in most cases. Once a mass has been shown to be solid and vascularised and not occurring in a context suggesting an inflammatory pseudotumour, it can be put, using CT, into one of the four categories of the classification that we propose: pseudotumoral dysmorphisms (type 1); typical high-fat angiomyolipomas (type 2); suspect indeterminate tumours (type 3); typically malignant tumours (type 4).

Is segmental enhancement inversion on enhanced biphasic MDCT a reliable sign for the noninvasive diagnosis of renal oncocytomas?

OBJECTIVE

The objective of our study was to retrospectively determine whether segmental enhancement inversion or other CT patterns seen at enhanced biphasic MDCT are predictive for the diagnosis of renal oncocytoma.

MATERIALS AND METHODS

Twenty-nine patients with 32 oncocytomas diagnosed by either biopsy or resection who had undergone enhanced biphasic CT between January 2004 and March 2010 were included in this study. Biphasic CT scans were analyzed for the presence of segmental enhancement inversion. Segmental enhancement inversion was defined as a renal mass with two distinctive segments in which the attenuation of the segments changed between the two phases of CT. The masses were further characterized on imaging to determine if any imaging feature is predictive of renal oncocytoma.

RESULTS

Of the 32 renal oncocytomas, 16 oncocytomas were eliminated from analysis. These masses were eliminated because they were larger than 4 cm (n = 4), the CT examinations were inadequate (n = 10), or the pathology results were questionable (n = 2). The remaining 16 tumors (mean size, 2.6 cm; range, 1.8-3.9 cm) were included in our study. Only two tumors showed distinct segments of variable degrees of enhancement, with one of those tumors having segmental enhancement inversion. Three masses had a central region of low density. The most common feature, identified in eight of the 16 oncocytomas, was a slightly heterogeneous mass that became homogeneous on the later phase of CT. Three oncocytomas had a homogeneous appearance on both phases.

CONCLUSION

Contrary to a prior report, we did not find segmental enhancement inversion to be a characteristic enhancement pattern of small renal oncocytomas on biphasic MDCT. We found no specific features on biphasic CT that could be considered reliable and could strongly suggest the diagnosis of renal oncocytoma.

[Hybrid renal tumors: a report of two patients]

PURPOSE

Renal hybrid tumors (HT) are characterized by the association of both oncocytes- and chromophobe-cells within the same tumor. They have been reported in patients with Birt-Hogg-Dube (BHD) syndrome. The aim of this report was to describe two cases of HT and summarize recent literature.

PATIENT AND METHOD

Case study was summarized from the patient's medical chart. Review of literature was performed using the National Center for Biotechnology Information (NCBI) database.

RESULTS

Two patients were diagnosed with multiple but small tumors of the kidney, and were treated with partial nephrectomy. Pathological analysis of these tumors showed oncocytoma-like and chromophobe-like cells intermixed in the same stroma.

CONCLUSIONS

HT may constitute a spectrum of tumors between renal oncocytoma and chromophobe renal cell carcinoma. From a pragmatic management perspective, it would be appropriate to consider such tumors as chromophobe carcinoma. In case of HT, a genetic study for BHD syndrome can be proposed to family relatives.

[Post-transplant renal tumors: a report of three cases]

We report three cases of primary renal tumors occurring on post-transplant kidneys, after a delay of 4, 8 and 12 years respectively following transplantation in a population of 1134 post kidney transplant followed at our institution. All three tumors underwent early detection because of the yearly ultrasound evaluation recommended for all post kidney transplant patients. The diagnosis was suggested by CT in all three cases but confirmed by preoperative percutaneous biopsy in two cases. The final pathology results confirmed two cases of clear cell renal carcinomas and one case of oncocytoma. Tumorectomy was undertaken for all three patients with successful results in two cases and return to hemodialysis in the third patient with a 4 cm tumor with mass effect on the collecting system.

[Role of contrast enhanced US in the evaluation of renal tumors]

PURPOSE

To evaluate the role of contrast enhanced US in the characterization of renal tumors. Materials and methods. Eighty-six renal tumors (33 solid, 53 cystic) underwent contrast enhanced US after indeterminate CT/MRI (67 lesions) or US (19 lesions). Pathological correlation was available for 42 cases, and follow-up at 3 and 6 months was available for 13 cases. Diagnosis was achieved in 21 cases. Lesions included: 19 renal cell carcinomas (4 conventional, 14 papillary, 1 tubulocystic), 5 oncocytomas, 3 metastases, 6 pseudomasses, and 53 cystic lesions including 6 malignant tumors.

RESULTS

Solid tumors were correctly identified in 100% of cases. Characterization of solid tumors was possible with specificity of 92.9% for papillary carcinoma, 57.1% for clear cell carcinoma, and 100% for oncocytoma. The specificity for distinguishing solid benign from solid malignant tumor was 100% based on the presence of hypoechogenicity relative to normal renal parenchyma on delayed imaging. Contrast enhanced US allowed reclassification of 23 indeterminate lesions on conventional US. It is of limited value for large cystic lesions or cystic lesions with extensive wall calcification.

CONCLUSION

Contrast enhanced US is easily performed in clinical practice and allows improved characterization of some renal tumors compared to other cross sectional imaging techniques.

Hybrid tumour 'oncocytoma-chromophobe renal cell carcinoma' of the kidney: a report of seven sporadic cases

OBJECTIVES

To determine whether renal hybrid tumours (HT) appear as a specific clinical and radiological entity, as HT are characterized by the association of both oncocytes and chromophobe cells within the same tumour, and have been described in patients with oncocytosis and Birt-Hogg-Dube syndrome.

PATIENTS AND METHODS

We reviewed the medical charts of 67 patients who had a partial or radical nephrectomy in our institution for renal oncocytoma (RO, 24), chromophobe renal cell carcinoma (CRCC, 36) and HT (seven), from January 2006 to October 2007. We report the clinical, radiological and pathological characteristics of the seven cases of HT.

RESULTS

The mean (range) age of the patients was 56 (41-68) year. None of the seven patients had any suspicion of RO, based on computed tomography (CT). Two patients had a history of kidney cancer. Five patients had partial and two a radical nephrectomy. The mean (range) maximum tumour diameter was 5.5 (1.8-9) cm. Two tumours were pT1a, two were pT1b and three were pT2. Pathological analysis showed RO-like and CRCC-like cells intermixed (six patients) or distinct (one). After a median (range) follow-up of 20 (8-25) months, none of the patients had any evidence of disease recurrence.

CONCLUSIONS

In a large series of patients with sporadic RO and CRCC, 10% of the tumours had hybrid morphological features, as described in oncocytosis and Birt-Hogg-Dube syndrome. We were unable to identify any specific clinical characteristic. Most importantly, none of these HT showed any of the radiological characteristics of RO.

[Renal tumors]

This pictural essay presents the different imaging patterns of the main renal tumor processes described in the latest pathological classification. Most of them make it possible to suggest certain histological types in order to modify the surgical approach.

[WHO classification 2004: tumors of the kidneys]

New entities, confirmed either by cytogenetic findings or by new molecular markers, have been included in the WHO 2004 renal tumor classification. Moreover, imaging improvements provide a better radiologic description of tumors. In this article, we will discuss the WHO 2004 classification and focus on the new entities and their macroscopic appearance. We will especially insist on the following entities: multilocular clear cell renal carcinoma, Xp11 translocation carcinoma, low-grade mucinous tubular carcinoma, epithelioid angiomyolipoma, and benign mixed epithelial and stromal tumor. We also discuss the new concept of hybrid oncocytoma and chromophobe renal cell carcinoma, as well as the Birt-Hogg-Dube syndrome, which is associated with kidney tumors.

[Renal angiomyolipoma complicated by extension to the renal vein and inferior vena cava]

Renal angiomyolipomas are renal hamartomas. They are usually found incidentally, presenting as well-defined echogenic masses on sonography and fat containing tumors on CT and MRI. We report a case of angiomyolipoma with sonographic and CT evidence of extension to the renal vein and inferior vena cava.