A Presumed Metastatic Lung Lesion Unveiling a Second Primary: Renal Cell Carcinoma With Coinciding Invasive Mucinous...

Multiple primary cancer is a self-explanatory term, albeit very uncommon. In most instances, when patients have a malignancy, the possibility of metastasis should be considered. Renal cell carcinoma (RCC) is one such cancer. However, as unlikely as it is, there is always a chance that another separate, unrelated malignancy could be present. Here, we would like to discuss a unique case of a 66-year-old female who not only developed primary RCC but also primary invasive mucinous adenocarcinoma of the lung. This revelation prompted a change in management, resulting in the medical team treating the two malignancies separately via surgical intent as opposed to treating metastatic RCC, which is more geared toward systemic medical therapy.