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The history of twenty-year long standing nodule argues strongly against a metastatic disease. Nonetheless this is a metastatic renal cell carcinoma. It is hard to speculate as to what was present in that area for twenty years. The histology did not show anything beside the metastatic nodule.
Cancer metastasis to the oral cavity is neither specific nor common. Although such cases constitute less than 1% of all oral malignant neoplasms, it may have a devastating result to the patient mainly because metastasis to other sites has already developed or is inevitable. Theoretically, any malignant neoplasm can metastasize to the oral cavity, but in actuality few do and of the ones that do, the majority are carcinomas rather than sarcomas. The most common malignant neoplasms that metastasize to the mouth are from the breast, lung, kidney, prostate and colon. Malignant neoplasms from the pancreas, esophagus, thyroid, cervix, and liver have also been described. Breast cancer is the most common neoplasm to metastasize to the oral cavity altogether. Lung and prostate cancers are the most common neoplasms to metastasize to the oral cavity in men. In most cases, the oral presentation is a secondary diagnosis when the primary diagnosis of malignancy in a distant organ has been already made and the patient has had or is undergoing treatment for it. In rare cases, the oral lesion is the first manifestation of the disease. By far the most common location is the posterior mandible, where 80% of cases occur, followed by the gingiva. This condition is mostly described in adults over the age of 30 and rarely in children. Pain and swelling are the most common clinical symptoms. Metastatic lesions may also present as asymptomatic, simulating a periapical lesion, or with gingival swelling like a pyogenic granuloma. They can cause anesthesia and parasthesia, especially when they involve the inferior alveolar canal. The latter results in so-called "numb-chin syndrome." Tooth loosening, displacement and sharp resorption have also been described. The radiographic appearance of the borders can range from moderately well demarcated to diffusely irregular. The majority of neoplasms cause bony destruction with ill-defined borders; the moth-eaten appearance of some bony destruction indicates aggressive behavior. It is also important to mention that at times, well-demarcated lesions with a benign morphology, as well as cystic radiographic morphology, have also been described. Metastatic neoplasms from the prostate and, rarely, from the breast can be bone-forming, resulting in radiopaque or mixed radiolucent and radiopaque lesions misdiagnosed as benign fibro-osseous lesions. Tumor metastasis to the oral cavity carries a poor prognosis because the oral cavity is usually not an isolated site and tends to project a more disseminated clinical behavior. Patients are typically treated with chemotherapy and the five-year survival rate is poor.