S3611 Gastric Metastasis Masquerading as a Polyp

Abstract

Introduction: Renal cell carcinoma (RCC) is the most common renal tumor and accounts for 3% of all cancer deaths. Gastric metastasis is a rare event with a reported incidence of 0.2 - 0.7% . There are less than 60 cases of gastric metastasis from a renal cell carcinoma. We present a rare case of a metastatic lesion appearing as a gastric polyp and the importance of the necessity of polypectomy regardless of size during any endoscopy. Case Description/Methods: 78 year-old male status-post radical nephrectomy 22 years ago for renal cell carcinoma and pulmonary metastasis 8 years ago presented with dysphagia. Patient has been actively followed by oncology and maintained on pazopanib for 10 years. EGD found 2 large polyps in the proximal gastric body along the greater curvature >1 cm. Pathology showed positivity for CAM5.2 and PAX8, confirming the diagnosis of a clear cell type of RCC. Discussion: Renal cell carcinoma even if treated with radical nephrectomy can become metastatic and recur 30% of the time. Metastatic renal cell carcinoma (mRCC) commonly metastases to the lung (70%), bones (30-40%), liver (20%), adrenal (10%), and brain (8%) [3-5]. Gastric metastases are exceedingly rare (< 1%). A systematic review by Prudhomme et al. identified 38 cases of RCC in the stomach between 1950- and 2018, and 73% presented with multiple metastatic sites (mainly lungs and bones). In spite of radical nephrectomy, given possible microvascular metastases of mRCC, unusual lesions should always be biopsied for malignancy. Given mRCC’s variable dormant nature, regardless of chemo-therapy status, clinicians should not hesitate to rule out possible mRCC as lesions can have very slow growth rate ranging from 0.31–211.93 cm^3/year and may be clinical silent for decades. Due to mRCC slow-growing nature, they result in several false-negative chest X-ray/abdominal CT screenings within the first 10 years and mRCC may re-surface decades later with alarm symptoms. Slow growing metastasized lesions are still malignant; the patient’s malignant polyp may have been growing 0.045cm/year for two decades. The minimum size cutoff for polypectomy is clinician-dependent with some guidelines recommending a 2-cm minimum and others recommending resection of all polyps greater than 0.5 cm. In patients with noted history of mRCC, regardless of size, all polyps should be biopsied.