As a result of development in medical diagnostic technology, the incidence of double primary cancer is increasing. In case that one primary cancer was identified by pathologic finding and has suggestive multiple metastatic lesions of the cancer, it is often difficult that the lesions are considered as another synchronous primary malignancy, not as metastasis of primary cancer. Here, we report a rare case of synchronous double primary renal cell carcinoma that was diagnosed initially as metastatic duodenal adenocarcinoma. A 66-year-old man presented with a palpable abdominal mass. Abdominal computed tomography showed duodenal wall thickening and hypervascular masses in the liver and left kidney. Esophagogastroduodenoscopy revealed an ulcerative lesion in the duodenal bulb, and endoscopic biopsy identified moderately-differentiated adenocarcinoma. We regarded the findings as duodenal adenocarcinoma with metastasis to liver and kidney. So he was treated with fluoropyrimidine-based chemotherapy for the diagnosis of duodenal adenocarcinoma with liver and renal metastases. After 10 months, he developed a right forearm mass. Morphological and immunohistochemical analysis of an incisional biopsy of the forearm mass were consistent with a diagnosis of metastatic renal cell carcinoma. Even when there is a pathologically confirmed malignancy, clinicians must consider the possibility of synchronous double primary malignancy in metastatic lesions.

Paraneoplastic neurological syndromes (PNS) are the remote effects of cancer on the nervous system. These may affect the nervous system from cerebral cortex to neuromuscular junction and muscle, causing damage to one or multiple areas. Among the various papraneoplastic neuropathies, the classical syndrome of PNS is subacute sensory neuronopathy involving the sensory neuron cell bodies in the dorsal root ganglia. In general, cases with paraneoplastic sensory neuronopathy are associated with small cell lung cancer. The authors experienced a case of an atypical unilateral paraneoplastic sensory neu-ronopathy associated with primary breast adenocarcinoma and lung metastasis, which is worthy of reporting.

Primary adenocarcinoma is a rare neoplasm of the urinary bladder, constituting approximately 2.5% of all primary bladder malignancies. Signet ring cell variant is even rarer, constituting approximately 0.5% to 2.0% of all primary carcinoma of the urinary bladder. However, glandular differentiation in the urinary bladder is relatively more common than primary adenocarcinoma of the urinary bladder. Therefore, diagnosis of primary adenocarcinoma of the urinary bladder can be very challenging, but of significant clinical importance. We report on a case of adenocarcinoma with mucinous and signet ring cell differentiation in the bladder dome in a 49-year-old female.