Crossed fused renal ectopia is a rare congenital anomaly resulting from embryological alterations, in which the ectopic kidney is contralateral to the insertion of its ureter into the bladder. This condition is generally asymptomatic, however, it is associated with renal complications and is usually found incidentally in radiological and molecular imaging studies. There are few reports in the literature demonstrating the combined results of molecular imaging and hybrid studies of this condition. This study aims to demonstrate the findings of static renal scintigraphy with 99mTc-DMSA, including SPECT/CT images, and dynamic renal scintigraphy with 99mTc-DTPA in a patient with crossed fused renal ectopia.

A 54-year-old female patient was diagnosed with stage IVa squamous cell carcinoma of the cervix causing right hydronephrosis due to extrinsic obstruction, requiring the placement of a double-J catheter. During the investigation, the patient was submitted to renal scintigraphy with 99mTc-DMSA, with SPECT/CT images, and dynamic renal scintigraphy with 99mTc-DTPA. Static images were obtained in the anterior, posterior, anterior and posterior obliques, and lateral abdominal projections and SPECT/CT images after 3 hours of intravenous injection of 99mTc-DMSA. A left ectopic kidney fused to the right kidney was observed, located to the right of the midline. Tubular function was normal in the left kidney and markedly decreased in the right kidney. Bilateral renal scars were detected. After 5 days, sequential images were acquired at intervals of 2 seconds for 1 minute and every 15 seconds for 25 minutes, in the anterior and posterior abdominal projections, immediately after intravenous injection of 99mTc-DTPA, with additional images after furosemide intravenous injection. Markedly decreased glomerular function was observed in the right kidney, and normal function in the left kidney, with signs of crossed fused renal ectopia (left ectopic kidney) and pyelocalyceal dilation on the right, with obstructive pattern.

Crossed fused renal ectopia is a rare condition. Scintigraphy images with 99mTc-DMSA and 99mTc-DTPA allow accurate evaluation of the various functional alterations of the kidneys resulting from this anomaly. Obtaining SPECT/CT images with 99mTc-DMSA contributes to the good correlation between functional and anatomical changes of the disease. 99mTc-DMSA and 99mTc-DTPA images are also useful for evaluation of tubular and glomerular renal function in crossed fused renal ectopia. Additionally, the anatomical and functional correlation with the hybrid SPECT/CT method enables the evaluation of abnormalities with more precision.