Papillary Renal Cell Carcinoma: Radiologic-Pathologic Correlation and Spectrum of Disease

Abstract

Papillary renal cell carcinoma (pRCC) is the second most common type of renal cell carcinoma (RCC). pRCC has unique imaging and clinical features that may allow differentiation from clear cell RCC (cRCC). There have been significant advances in our knowledge of the natural history and treatment of pRCC, with data suggesting that it may be best to manage pRCC differently from the other subtypes of RCC. At contrast material-enhanced computed tomography, pRCC enhances less than does cRCC in all phases of contrast-enhanced imaging. The difference in the degree of enhancement between pRCC and cRCC is due to differences in their intratumoral vascularity. In general, if a heterogeneous mass enhances to a degree similar to that manifested by the renal cortex, it is likely to be a cRCC. A mass that enhances to a lesser degree is likely to be a non-clear cell RCC. It is common for metastatic lesions from pRCC to show enhancement characteristics similar to those of the primary tumor and be hypovascular.

Renal Cortical Tumors: Use of Multiphasic Contrast-enhanced MR Imaging to Differentiate Benign and Malignant Histologic Subtypes

“…Both papillary carcinomas and angiomyolipomas tend to be T2-hypointense compared with the adjacent renal parenchyma, while clear cell carcinomas are iso-to hyperintense (36)(37)(38). Furthermore certain features such as the presence of intralesional fat are characteristic of angiomyolipomas.…”

Intraoperative abdominal ultrasound in oncologic imaging

“…Nephron-sparing procedures have become the treatment of choice for T1 renal tumors and recent data suggests that PN may be as effective as radical nephrectomy for larger renal tumors [22] . These nephron-sparing procedures rely on radiology to precisely define size and location of the renal tumors, as well as extension or involvement of the renal sinus fat, and vessels and the hilum of the kidneys [19,23] . Besides state-of-the-art preoperative MDCT or MRI, IOUS is routinely utilized in our institution in the vast majority of nephron-sparing surgeries.…”

“…About 30% of RCCs are markedly hyperechoic and virtually indistinguishable from small angiomyolipomas. Most are hypervascular in relation to the renal parenchyma, but chromophobe RCCs are typically hypovascular [13,21,23] . Cystic RCCs usually show discrete solid mural nodules with internal vascularity or thickened irregular septations.…”

“…Intraoperative ultrasound is of great value to accurately identify small completely intrarenal tumors, ensuring that the lesion is in the center of the resected specimen, and that a safe margin free of tumor is obtained on all sides [7,23] . This requires careful scanning and the surgeon often marks the renal surface with electrocautery at the location indicated by the radiologist.…”

“…Its sensitivity, and specificity for detection of renal sinus invasion and venous invasion is very high, approaching 100% [25] . Centrally located renal masses abutting the renal hilar vessels, collecting system or renal pelvis may preclude a nephron-sparing procedure, since a negative margin may not be feasible [7,19,20,23] . The pyramids, calyces, infundibula, and the renal sinus fat are readily identified on intraoperative ultrasound and tumor involvement of these structures must be commented upon and relayed to the surgeon at the time the examination is being performed.…”