Nuclear Medicine Service, Hospital Universitario Miguel Servet, Zaragoza, Spain
Keywords: cake kidney; diagnosis; function follow-up; single ureter; Tc-99m MAG3 diuretic renogram
Renal history
A 38-year-old man with history of spina bifida, L4S1 discopathy and azoospermia presented with fever and abdominal pain suggestive of urinary tract infection. An ultrasound showed a cake kidney in the pelvis. Intravenous urography, CT and MRI visualized the cake kidney overlying the bladder and drained by single short ureter, with hydronephrosis caused by apparent pelviureteral stenosis (Figs 1 and 2
). A Tc-99m MAG3 diuretic renogram showed a single pelvic kidney with delayed excretion of the radiotracer (Fig 3
and 4A
). Subsequently, a pyeloplasty was performed. Three months later, renal function was re-assessed by Tc-99m MAG3 diuretic renogram and complete retention of the radiotracer was observed (Fig. 4B
). Because of the ureteric obstruction a pyelovesicostomy was performed.
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Discussion
The synonymous term fused pelvic kidney, cake kidney or lump kidney is defined as an anomaly in which the entire renal substance is fused into one mass, lying in the pelvis, and giving rise to two separate ureters which enter the bladder in normal relationship [1]. This is a rare congenital anomaly of the genitourinary system, and even more so if the kidney is drained by a single ureter, a finding that has been previously reported in only four patients [2]. Renal ectopias may occur simultaneously with other organ malformation [2], and spina bifida was present in our patient.
Cake kidney malformation is not necessarily associated with renal dysfunction or a portend of progressive deterioration of renal function [1], but does require exclusion of concomitant anomalies, long-term follow-up of renal function, and early detection of possible future complications such as obstruction, infection, or calculi. These requirements can be fulfilled by MAG3 diuretic renogram as this technique provides simultaneous kidney visualization and assessment of renal function. Moreover, MAG3 renogram has successfully detected a cake kidney when the nature of the abdominal lump was initially not clear [3]. MAG3 diuretic renogram is a helpful non-invasive cheap tool for diagnosis and long-term follow-up of renal function in cake kidney.
Notes
Correspondence and offprint requests to: Anabel Cortés Blanco, Domingo Ram 32, 3F, Zaragoza, E-50017, Spain.
References