Imaging patterns of atypical renal cell carcinoma recurrence: a pictorial review

Renal cell carcinoma accounts for 2% of all adult malignancies [1]. This cancer exhibits a highly variable constellation of presenting signs and symptoms, and, in 25% -40% of cases, is actually diagnosed as an incidental finding [1]. In patients with localized disease at presentation and who are treated surgically, distant metastases still develop in 20%-50% [1-4]. Although 85% of relapses occur within 3 years, recurrence may occur over an unpredictable time frame, up to and beyond 10 years after resection [1]. Common sites of recurrence include lung, liver, bone, and brain. However, this cancer also has a predilection for reappearing in unusual sites, presenting both clinical and radiologic diagnostic challenges if the original diagnosis is not borne in mind. If detected in a timely manner, then such isolated metastases may be curatively resected [4,5]. Survival advantage is conferred on those with a longer disease-free interval and a single site of recurrence [4,5]. This pictorial review of unusual sites of disease recurrence, both local and metastatic, diagnosed at our institution, highlights the need for an awareness of the variety of atypical manifestations of renal cell carcinoma recurrence. Methods We reviewed both the radiologic and urologic databases of patients who presented with recurrence of renal cell carcinoma to our institution over the past 10 years, a total of 634 patients. The majority of these patients were found to have local nephrectomy bed recurrence of tumour or disease metastatic to the typical sites, such as lung or bone. The more unusual and unexpected patterns of disease recurrence were subselected for this pictorial review. We illustrate the imaging features of an extensive array of atypical locations of renal cell carcinoma metastases and unusual manifestations of local recurrence on computed tomography (CT), magnetic resonance imaging (MRI), ultrasound, positron emission tomography-CT, and plain film. (author)