Metastatic renal clear cell carcinoma mimicking a gallbladder polyp: Case report and literature review

INTRODUCTION: Metastatic tumors to the gallbladder are uncommon. Metastases from renal cell carcinoma (RCC) to the gallbladder are exceptional. Frequencies of less than 0.6% reported in large autopsy reviews and few cases have been reported in the literature. PRESENTATION OF CASE: Herein we present a case of a 50-year-old man that developed four years after radical nephrectomy for RCC, a gallbladder metastasis, discovered incidentally on Computed Tomography (CT) scan. It was described as an intraluminal gallbladder polyp. Radiological features were very suggestive of primary gallbladder carcinoma, thus the patient had a laparoscopic cholecystectomy. The pathological examination of the surgical specimen concluded to a RCC metastasis. Immunochemistry with vimentin and pancytokeratin were supportive of this diagnosis. The clinical course was uneventful after 18 months period of follow up. DISCUSSION: At the time of presentation, almost one-third of the patients with RCC are metastatic. Metastases to the gallbladder are extremely rare. Clinical presentation and physical examination are unspecific. Radiological findings can raise information and orient the diagnosis although the difference between both diagnoses remains difficult. Usually, it is a pedunculated and not associated with gallstones with enhancement on CT scan. The treatment remains surgical with R0 cholecystectomy, and prognosis is mainly related to disease free interval and single site metastasis. CONCLUSION: We highlight here the challenge to make the difference between a primary gallbladder carcinoma and metastasis from RCC. Diagnosis is made on pathological examination and immunochemistry.