Imaging of pancreatic metastases from renal cell carcinoma

Abstract

Background To describe the main imaging characteristics of pancreatic metastases from renal cell carcinoma (RCC) with particular attention to CT features, underlining possible criteria for a differential diagnosis. Methods 15 patients have been included in this study. 14 patients underwent multislice CT with triphasic acquisition (unenhanced, pancreatic parenchymal and portal venous phases). In 9 cases a delayed phase (120 sec) was also acquired. 5 patients underwent MRI, before and after administration of gadolinium. Results The mean time interval between nephrectomy and recurrence was 7.5 years (range 1-17 years). On CT metastases avidly enhanced in the parenchymal phase and then demonstrated a significant wash-out, approaching isodensity to the normal pancreatic parenchyma in the portal phase. In the portal phase 20 of the 25 lesions found in the arterial phase were recognizable. On non-enhanced scans, only 13 of the 25 lesions were detected. On MRI, with the limitations due to the paucity of cases, the metastatic foci appeared hypointense to normal pancreatic tissue on T1-weighted images, and hyperintense on T2- and diffusion-weighted images. After gadolinium, the behaviour was similar to that reported for CT, except for one patient in whom two metastatic foci presented a signal intensity almost isointense to the surrounding parenchyma, accompanied also by an unusual lowering of the signal on DWI (diffusion-weighted imaging) with high b-values. Compared to CT, with MRI the lesions appeared all detectable even on non-enhanced acquisitions. Conclusion Renal Cell Carcinomas require a prolonged CT or MRI follow-up. In patients with RCC history, an early arterial or a pancreatic parenchymal phase is always mandatory, as pancreatic metastases typically present themselves as hypervascular lesions. This behavior is similar to that of neuroendocrine tumors, while the other primary pancreatic tumors tend to be hypovascular.

A Plea for Surgery in Pancreatic Metastases from Renal Cell Carcinoma: Indications and Outcome from a Multicenter Surgical Experience

“…Occasionally, metastases may have occurred earlier and been overlooked by the cross-sectional imaging studies [ 9 ]. The gold standard to detect hyper vascular RCC-PMs in the follow-up of RCC patients should be the CT scan, and MRI could be an acceptable alternative option [ 8 ]. One third of our patients developed RCC-PMs after a DFI of more than 10 years; a long follow-up over 10 years should be considered, even in asymptomatic patients.…”

“…Currently, a total body functional imaging is not part of the routine follow-up of these patients, although the systemic spread of RCC is well known. Both on CT scan and MRI, RCC-PMs show an early enhancement after contrast medium injection; MRI can detect RCC-PMs even without contrast-enhancement, as hyper intense lesions at T2- and diffusion-weighted images [ 8 ]. These imaging features are common to both RCC-PMs and pancreatic neuroendocrine neoplasms (pNENs), and the differential diagnosis with a non-functioning pNEN may be challenging [ 9 ].…”

Intrapancreatic accessory spleen mimicking malignant tumor: three case reports

“…In general, diagnosing RCC in the pancreas usually relies on findings from CT and ultrasonography. Most RCC are hypo- to isodense on unenhanced CT, are often hyperdense in the arterial phase, and iso- to hyperdense in the venous phase (8). Most cases do not present with clinical symptoms but are recorded during follow-up or accidentally on CT scan for other indications, but clinical manifestations could be upper abdominal pain, fatigue, loss of appetite, and other unspecific symptoms (9).…”

CT diagnosis for metastasis of clear cell renal cell carcinoma to the pancreas

“…[5,7,15] On unenhanced CT, most foci showed nodules or masses with low or mildly low density, while a few foci could be equal density and not detected. [16] Small tumors are usually confined in pancreas, while large tumors are more likely to stick out of pancreas. Thus, the maximum diameter of most small focus is inside the pancreas.…”

“…[5,15] The enhanced level and mode of most foci are similar to primary CCRCC usually, and show significant enhancement in artery phase, while decreased enhancement in venous phase. [5,15,16] However, the enhancement may be still apparent relatively in venous phase in some cases. [16] Finally, they usually showed obviously declined enhancement in delayed phase.…”