Fat Necrosis Mimicking Renal Cell Carcinoma Recurrence Following Cryotherapy, Partial Nephrectomy, and Nephrectomy.

Objective: To present our experience with three patients surgically treated for suspected recurrent renal cell carcinoma whose final pathology was consistent with tumefactive fat necrosis.

Methods: Three patients underwent definitive therapy for biopsy proven renal cell carcinoma (cryoablation, partial nephrectomy, and nephrectomy) and later demonstrated evidence of recurrent renal cell carcinoma on follow up imaging. All three patients underwent surgical resection of the suspected recurrences with final pathology consistent with tumefactive fat necrosis.

Results: The three patients were 60, 74, and 39-years old, respectively. The previous definitive therapies for renal cell carcinoma were percutaneous ablation, RAPN, and nephrectomy. Each patient had previous surgical pathology that confirmed prior renal cell carcinoma. Signs of recurrence on diagnostic imaging occurred 2 years, 23 months, and 8 months post-definitive therapy.

Conclusion: In patients with a history of renal cell carcinoma, consideration of fat necrosis should be taken into account upon seeing imaging concerning for tumor recurrence. Continued analysis of cases with such a diagnosis will be beneficial in recognizing this possibility to avoid unnecessary surgery or therapy when possible.