FDG-PET/CT detected occult metastatic disease in seven of 42 patients with negative conventional preoperative evaluations. PET findings were strongly correlated with survival. As such, FDG-PET/CT may help in making treatment decisions before radical cystectomy.

Renal cell carcinoma (RCC) is the most common malignant tumor involving the kidney. Determining the subtypes of renal cell carcinoma is among the major goals of preoperative radiological work-up. Among all modalities, magnetic resonance imaging (MRI) has several advantages, such as inherent soft tissue contrast, detection of lipid and blood products, and excellent sensitivity to detect small amounts of intravenous contrast, which facilitate the discrimination of subtypes of RCC. In this article, we review MRI and pathological features used for determining the main histologic subtypes of RCC, including clear cell, papillary, collecting duct, chromophobe, multilocular cystic, and unclassified RCC. Renal cell carcinoma (RCC) is the most common malignant epithelial tumor of the kidney, accounting for 85%-90% of all solid renal tumors in adults and comprising 1%-3% of all malignant visceral neoplasms (1). Approximately 40% of patients with RCC eventually die from progression of this disease, making it the most lethal urologic malignancy (2). Today, most RCC instances are incidental masses identified on imaging studies performed for nonurological reasons.Percutaneous biopsy is a minimally invasive method, and its accuracy for identifying renal tumors ranges from 70% to 90% (3, 4). However, widespread use of percutaneous biopsy remains controversial due to the potential complications of biopsy, the possibility of sampling errors, the dependence on an adequate biopsy sample for analysis, and concerns about how the biopsy information might alter the treatment plan (5). Therefore, histopathological characterization of renal masses with magnetic resonance imaging (MRI) compared with percutaneous biopsy becomes more advantageous.Determining subtypes of RCC has significant prognostic and theraupeutic implications for patients who are poor surgical candidates, for patients who have a metastatic disease, for surgical planning in patients who are surgical candidates, and for immunotherapy and use of the tyrosine kinase inhibitors "sunitinib" and "sorafenib" for clear cell RCC and "temsirolimus" for papillary RCC (6-9).The need for a different approach to the management of RCC among classical surgical procedures has arisen. Nephron-preserving surgical methods, cryoablation, radiofrequency ablation, targeted molecular therapy or follow-up, and MRI are believed to surpass other modalities both in the diagnosis of RCC and determination of its subtypes (10,11).In this article, we review MRI findings and pathological features used for determining the main histologic subtypes of RCC, including clear cell carcinoma, papillary, collecting duct, chromophobe, multilocular cystic, and unclassified RCC. The role of MRI in renal imagingThere are three indispensable components of renal MRI: breathhold imaging, three-dimensional (3D) gradient echo pulse sequence, and fat detection techniques.Breathhold imaging is one of the essential techniques in renal mass MRI protocols. Suspended expiration eliminates respiratory motion artifacts an...

In hyperechoic renal masses, the presence of shadowing, a hypoechoic rim, and intratumoral cysts are important findings that may help distinguish AML from RCC.

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Primitive neuroectodermal tumor (PNET), the second most common type of sarcoma in the first two decades of life, rarely presents as an organ-based neoplasm. Rather, it is seen typically in the soft tissues of the chest wall and paraspinal region. We report a case of primary PNET of the kidney in a 17-year-old girl who presented with abdominal pain, hematuria, and an abdominal mass. Nodules and sheets of monotonous-appearing primitive round cells and the formation of rosettes focally were the principal microscopic features. The tumor cells were uniformly immunoreactive for vimentin, cytokeratin, neuron-specific enolase, and 013 (CD99). In addition, the characteristic translocation of PNET and Ewing sarcoma, t(11;22)(q24;q12), was detected by polymerase chain reaction (PCR). Eight previous examples of renal PNET have been reported in the literature in the past 2 years, but only three of these cases have had complete immunohistochemical evaluation with the demonstration of 013 positivity. To our knowledge the present case is the only one to date demonstrating the recurrent translocation t(11;22)(q24;q12) by PCR. Assuming that the previous cases in the literature are bona fide examples of PNET, the kidney may be another site of predilection for this usual soft-tissue neoplasm. We are once again confronted with the dilemma about the nature of the progenitor cell.

Purpose To assess transvaginal coregistered photoacoustic tomography (PAT) and pulse-echo US for diagnosis of ovarian cancer based on functional parameters provided by PAT. Materials and Methods Between February 2017 and December 2017, 26 ovarian masses from 16 participants were successfully imaged in vivo by multispectral photoacoustic imaging, including nine invasive epithelial ovarian cancers (six serous carcinomas and three endometroid adenocarcinomas), three other tumors (two borderline serous tumors and one sex cord-stromal tumor), and 14 benign and normal (hereafter referred to as benign/normal) ovaries. The relative total hemoglobin concentration (rHbT) and mean oxygen saturation (sO) shown at PAT were used to characterize the ovaries identified at US. Results The average rHbT was 1.9 times higher for invasive epithelial cancers than for the benign/normal ovaries (P = .01). Additionally, the rHbT distribution was extensive in invasive epithelial cancers, but was scattered in benign/normal ovaries. However, the rHbT of two borderline serous tumors and one stromal tumor was in the same range as that of benign/normal ovaries. The mean sO of invasive epithelial cancers, and of the borderline and stromal tumors, was 8.2% lower than that of benign/normal ovaries (P = .003). Discussion Invasive epithelial ovarian cancers showed higher and extensive tumor vascularity and lower oxygen saturation than benign and normal ovaries. Two borderline noninvasive serous and one stromal tumor showed low oxygen saturation compared with benign and normal ovaries. ©RSNA, 2018 Online supplemental material is available for this article.