for the patient . Stage T3a represents RCC that has invaded into the renal vasculature or perinephric fat and can appear as a mass with irregular borders and contrast enhancement on CT imaging . 8 Renal vein involvement is associated with a decreased five-year survival , less than 60 %, compared to organ confined disease . 9
Determining that the mass is infectious rather than neoplastic is a crucial part of the diagnostic process , as the vast majority of renal masses in adults will be malignant . Patients with multiple risk factors for RCC such as diabetes , obesity , and hypertension who will be solely treated empirically for infection and not yet for malignancy , need to be closely monitored to determine if the worrisome imaging findings have resolved . 8 Our patient had risk factors for complicated pyelonephritis , but RCC had to be included in the differential diagnosis . The 14-day course of antibiotics and continued anti-coagulation therapy resulted in resolution of the abnormal findings on CT imaging ( Figure 2 ), which implied infection rather than malignancy . In other published reports , the same combination of pharmacologic management was found to be successful . 4 , 5 Through joint decision-making , the patient was amenable to the management choice , after considering the size of the renal mass ( if it were malignancy , there was a low risk of metastasis ) and the patient ’ s non-optimal condition at that time for major surgery . Since there was also the possibility of an infectious etiology , repeat imaging instead of biopsy was deemed to be safer and appropriate by the patient and the healthcare team . In patients who are good surgical candidates who present with a renal mass , joint decision making should also occur to determine if biopsy should be performed as recommended by the guidelines of the American Urologic Association . 10
CONCLUSION
Our case adds to the small number of such cases described in the literature and provides three main lessons : 1 ) RVT can accompany pyelonephritis , 2 ) renal abscesses can display contrast enhancements that mimics malignancy , and 3 ) antibiotic treatment plus anti-coagulant therapy can be an effective management in patients with acute pyelonephritis and RVT . It is
FIGURE 1 : Representative Abdominal and Pelvic CT Imaging
Figure 1a shows a 2.3 cm x 3.1 cm mass in the midportion of the right kidney with contrast enhancement areas of heterogeneity . Figure 1b shows a thrombus in the right main renal vein .
FIGURE 2 : Repeat Abdominal and Pelvic CT Imaging
Eight weeks after the initial CT showing resolution of both the right renal mass ( 2a ) and right renal vein thrombus ( 2b ).
imperative to emphasize to patients with renal masses diagnosed simultaneously with infection and thromboses that their condition and imaging must be re-assessed in six to 12 weeks , and that biopsy may be needed . This close follow-up will determine whether there is a more serious process ( such as malignancy ) occurring , or if the infection was the only cause of the abnormal CT findings .
REFERENCES
1 . Lurz KL , Hanna DN , McGreen BH , Schanne FJ . A rare case of renal vein thrombosis secondary to Klebsiella pneumoniae pyelonephritis . Urol Ann . 2018 ; 10 ( 1 ): 103-105 .
2 . Cancer of the Kidney and Renal Pelvis - Cancer Stat Facts . SEER . Accessed March 16 , 2020 . https :// seer . cancer . gov / statfacts / html / kidrp . html .
3 . Hsieh JJ , Purdue MP , Signoretti S , et al . Renal cell carcinoma . Nat Rev Dis Primers . 2017 ; 3:17009 .
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