Squamous cell carcinoma (SCC) of the renal pelvis is a particularly rare tumor that accounts for a minor portion of renal malignancies and is aggressive with an unfavorable prognosis. It is usually diagnosed after surgery and at advanced stages as it does not possess specific clinical and radiological properties. The pathological examination of a 38-year-old female patient who had undergone nephrectomy due to a nonfunctioning right kidney caused by long-standing staghorn calculus revealed moderately differentiated renal pelvis SCC invading the renal parenchyma. The patient who experienced severe lumbar pain in the second postoperative month presented lymphadenopathy, which could not be detected with ultrasonography but was diagnosed with F-18-fluorodeoxyglucose positron emission tomography/computed tomography ((18)FDG PET/CT). The patient received systemic treatment following the early diagnosis and survived past the average survival time. It was concluded that in cases where SCC was diagnosed after nephrectomy, investigating metastasis with (18)FDG PET/CT and initiating early systemic treatment in the presence of metastasis could contribute to survival.