Solitary Brain Lesion: An Unexpected Presentation of Urachal Adenocarcinoma.

Urachal adenocarcinoma (UA) is a rare and aggressive malignancy that typically presents at advanced stages and is associated with poor prognosis. We describe the case of a 63-year-old man with a history of UA treated with partial cystectomy seven years earlier, who remained under annual oncologic follow-up, with the last assessment nine months before the current episode. He presented with neurological symptoms initially suggestive of ischemic stroke. Brain magnetic resonance imaging (MRI) revealed a left cerebellar lesion, and due to its symptomatic nature and diagnostic uncertainty, surgical resection was performed. The biopsy showed metastatic adenocarcinoma, without definitive identification of the primary site. Subsequent staging identified only pulmonary lesions suggesting lung cancer; however, the diagnosis was made after a transthoracic needle biopsy, which confirmed UA in an advanced stage. The patient underwent whole-brain radiotherapy followed by systemic chemotherapy with fluoropyrimidine and platinum. Despite disease progression, he achieved prolonged disease control and preserved quality of life, living more than one year with an Eastern Cooperative Oncology Group (ECOG) performance status of 1 until the final weeks of life. This case shows that UA may present with late brain metastasis and supports a multidisciplinary treatment approach.