Pancreatic Metastases from Clear Cell Renal Cell Carcinoma: Diagnostic Insights from Endoscopic Ultrasound-Guided Fine-Needle Biopsy.

Clear cell renal cell carcinoma (ccRCC) is the most common type of kidney cancer, accounting for approximately 75-80% of all renal carcinomas, and is often diagnosed incidentally on abdominal imaging, such as abdominal ultrasound or CT scan. Among other types of renal cancer, ccRCC is recognized to be highly aggressive due to its metastatic potential, which leads to a poor prognosis and an increased mortality rate. The most common sites of ccRCC metastasis are the lung, lymph nodes, bone, liver, and adrenal glands. Clear cell RCC is the most frequent primary tumor associated with secondary pancreatic involvement, while overall, pancreatic metastases represent only 2-5% of all malignant pancreatic lesions. These metastases often occur many years after nephrectomy and may present as solitary or oligometastatic disease, frequently displaying a paradoxically favorable prognosis compared with other metastatic sites. The present narrative review we conducted emerged from presentations of ccRCC with pancreatic distant metastases, potentially labeled as primary pancreatic tumors on imaging studies, mimicking pancreatic neuroendocrine tumors due to the hypervascular nature of ccRCC. Four patients were investigated in our clinic for suspicious pancreatic lesions identified on CT imaging, involving both the head and body of the pancreas. The definitive diagnosis was established by performing endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) or fine-needle biopsy (FNB) and histopathological analysis of the collected tissue samples. Endoscopic ultrasound-guided fine-needle biopsy (EUS-FNB) has emerged as a pivotal tool for obtaining tissue diagnosis, particularly when cross-sectional imaging is inconclusive. Through a synthesis of clinical data and literature, this article underscores the essential diagnostic role of EUS-guided tissue acquisition and its impact on therapeutic decision-making.