Case Presentation: An 84-year-old male with oncologic history of oligometastatic ccRCC, metastatic prostate cancer and melanoma was found to have a 16mm enhancing, pancreatic head mass on evaluation of an infrarenal abdominal aortic aneurysm on computed tomography (CT). At age 61, he underwent a left radical nephrectomy for a 5 cm, Grade II ccRCC with extension into the main renal vein and renal pelvis (pT3aNx). Surgical margins were negative. Over the next two decades, he developed a single solitary RCC pulmonary metastasis that was fully resected. He did not receive systemic therapy. The pancreatic head mass, located anterior to pancreaticoduodenal groove, was further evaluated with Magnetic Resonance Cholangiopancreatography (MRCP) and Prostate-Specific Membrane Antigen Positron Emission Tomography (PSMA PET/CT). There was no increased avidity in the lesion, ruling out prostate cancer involvement with no additional lesions identified within the gastrointestinal tract. He underwent an esophagogastroduodenoscopy (EGD) and an endoscopic ultrasound (EUS), confirming the presence of the pancreatic lesion, as well as identifying a small superficial polyp within the gastric antrum. Biopsy of the pancreatic lesion was non-diagnostic, but pathology of the gastric polyp returned consistent with ccRCC. A repeat EUS with biopsies of the pancreatic mass is planned.
Discussion: The natural history of metastatic ccRCC can be unpredictable, but metastasis to the small bowel and gastric mucosa is exceedingly rare. Small, solitary lesions within the lumen of the bowel can be challenging to identify with conventional imagining. High clinical suspicion and direct visualization with EGD are often required. As well, histologically, ccRCC can appear similar to other carcinomas, including signet ring gastric carcinoma, with clear cell cytoplasm and loss of e-cadherin but can be differentiated from ccRCC based on additional staining. With increasing survivability of ccRCC, clinicians should be increasingly aware of the risk of rare metastases including to the gastrointestinal tract and communicate these concerns with pathology in order to further evaluate and confirm with pankeratin staining and CD10 staining. It will be a multidisciplinary team in order to identify these new locations of metastases of clear cell Renal Cell Carcinoma.
Conclusions: Gastric metastases of clear cell Renal Cell carcinoma is a very rare phenomenon. This case, incidentally identified upon endoscopic examination, and outside of the norm of typical metastases 24 years after the initial tumor is valuable for the clinician who continues to follow these patients. Unidentified causes of anemia or abdominal pain, or even erythematous mucosal lesions noted on scopes, should concern providers for a possible metastasis to the stomach.
