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Saudi Journal of Kidney Diseases and Transplantation
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Year : 2017  |  Volume : 28  |  Issue : 1  |  Page : 190-193
An atypical presentation of cake kidney

1 Department of Internal Medicine, "San Pellegrino" Hospital, Castiglione delle Stiviere, MN, Italy
2 Department of Radiology, "San Pellegrino" Hospital, Castiglione delle Stiviere, MN, Italy

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Date of Web Publication12-Jan-2017

How to cite this article:
Spatola L, Tonoli G, Visconti P, Carleo P, Di Sarra D, Sacco AP, Fainelli G, Boniotti V, Panzolato G. An atypical presentation of cake kidney. Saudi J Kidney Dis Transpl 2017;28:190-3

How to cite this URL:
Spatola L, Tonoli G, Visconti P, Carleo P, Di Sarra D, Sacco AP, Fainelli G, Boniotti V, Panzolato G. An atypical presentation of cake kidney. Saudi J Kidney Dis Transpl [serial online] 2017 [cited 2022 Aug 19];28:190-3. Available from: https://www.sjkdt.org/text.asp?2017/28/1/190/198277
To the Editor,

Cake kidney is one of the rarest congenital kidney disorders with a total incidence estimated at between 1:12.000 and 1:17.500 on autopsies. Usually, a cake kidney has two ureters with less than ten cases described in literature with a single ureter. Our case minded our attention because of the coexistence of two big cysts in the left kidney, an angiomyolipoma in the right one and a double left renal artery.

A 64-year-old diabetic man was admitted to our Unit for weakness and inadvertent fall due to hypoglycemic failure (glucose 40 mg/dL). The patient had post-ischemic dilated cardiomyopathy, heart failure (ejection fraction of 36%), and chronic kidney disease (CKD) with stable serum creatinine values of 1.7 mg/dL and estimated glomerular filtration rate (eGFR)

41.7 mL/min according to CKD-epidemiology collaboration (CKD-EPI). The patient had also prostatic hypertrophy with an indwelling urinary.

At admission, the blood pressure was 100/60 mm Hg, weight 90 kg, serum creatinine of

1.56 mg/dL, eGFR 46.3 mL/min CKD-EPI, hemoglobin 10 g/dL, white cells 11.67 × 10[3]/μL, and an asymptomatic urinary tract infection due to Escherichia coli (>100.000 UFC/mL).

The patient's had no previous renal evaluation. He only had one abdominal ultrasound examination during childhood, but he cannot remember the report thereof. We performed an ultrasound abdominal examination that revealed no kidneys in the retroperitoneal abdominal cavity, but an atypical kidney tissue image in the hypogastric area ([Figure 1]).
Figure 1. Kidney in the pelvis, complete fusion of the upper and lower poles.

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A computerized tomography (CT) with contrast agent after adequate hydration therapy was performed. The CT scan revealed the presence of a complete fusion of the two kidneys configuring a "cake kidney" in the pelvis, in the presacral region ([Figure 2]).
Figure 2. Cake kidney in the presacral area and a cyst of 85 mm in the lower pole of the left kidney.

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The "cake" kidney presented bilateral hydroureteronephrosis ([Figure 3]) with both ureters entering the bladder in the regions of the trigone, and a 62 mm cyst highlighted in the left kidney ([Figure 4]). An angiomyiolipoma was confirmed in the CT scan ([Figure 5]), and the left kidney showed also double renal artery ([Figure 6] and [Figure 7]).
Figure 3. Cake kidney with bilateral hydroureteronephrosis and a cyst in the left kidney.

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Figure 4. Another 62 mm cyst in the left kidney.

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Figure 5. Cake kidney in the pelvis, in the presacral region, and angiomyolipoma in the right kidney (the arrow point out the angiomyolipoma, density – 32).

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Figure 6. Right and left renal arteries (the arrow indicates the left artery, that origin from the abdominal aortic artery).

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Figure 7. The arrow indicates the accessory renal artery, whose origin belongs from the internal iliac artery.

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The patient was entered into a program of a renal and urological follow-up to control diabetes and renal function in the future. Patient informed consent was obtained before collecting figures.
"Cake Kidney" is one of the rarest congenital forms of renal fusion and it is almost invariably located in the midline in the pelvis.[1] The total incidence of "cake or lump kidney" is estimated to be between 1/12.000 and 1/15.700 autopsies.[2] It is not completely understood how it develops, but it may be due to the squeeze of the nephrogenic blastemas by the umbilical arteries at the 9 mm stage (about 30 days of gestation), and this could in part explain the fusion and the migration to pelvis.[3] A possible alternative explanation could be an abnormal growth of the ureteric buds into a common metanephric blastema.[4] Usually, cake kidneys present two ureters entering the bladder in the normal regions of the trigone[1], and the incidental diagnosis is fairly more common in males (male:female 2-3:1).[1] Less than ten cases of cake kidney with a single ureter have been described in literature[4] and represent a rarity of a rarity, and it could be due to a regression of the second ureteral bud following the fusion of the metanephric blastemas. Typical recurring histological malformations are immature glomeruli and dilated tubules[5]. Almost up to one-third show other associated non urogenital abnormalities of the cloacal derivatives that are called "Caudal regression syndrome" also known as caudal dysplasia or sacral agenesis syndrome.[5]

Usually, cake kidneys are never operated on, in the absence of complications, because of the dislocation and position of blood vessels, and the secondary potential risk of renovascular hypertension. In addition, other possible vascular complications, such arterial or vein thrombosis are also described as potential cause of death.[2] Cake kidneys are generally asymptomatic or associated with urinary tract infections[2], and this was the first case with both an angiomyolipoma and a double renal artery described in literature.

Congenital anomalies of the kidney and urinary tract account for 20%-30% of all congenital malformations and include relative rare forms of renal fusion disorders. These uncommon forms of renal diseases are still an incidental or autoptic diagnosis, and their pathogenesis is far from being completely clear.

Conflict of interest: None declared

   References Top

Bauer SB. Anomalies of the kidney and ureteropelvic junction. In: Walsh PC, Retik AB, Vaughan ED, Wein AJ, editors. Campbell's Urology. 7th ed., Vol. 2. Philadelphia: W. B. Saunders; 1998. p. 1708-55.  Back to cited text no. 1
Ignjatovic I, Stojkovic I, Dinic LJ, Jovanovic M, Ivanovic D. Bilateral fused pelvic kidney ectopia with a single draining ureter solved by craniolateral displacement of the kidney and Boari-modified bladder-calyceal anastomosis with bladder augmentation. Int J Urol 2007;14:552-4.  Back to cited text no. 2
Srivastava RN, Singh M, Ghai OP, Sethi U. Complete renal fusion ("cake"/"lump" kidney). Br J Urol 1971;43:391-4.  Back to cited text no. 3
Rosenkrantz AB, Kopec M, Laks S. Pelvic cake kidney drained by a single ureter associated with unicornuate uterus. Urology 2010;76:53-4.  Back to cited text no. 4
Kaufman MH, Findlater GS. An unusual case of complete renal fusion giving rise to a "cake" or "lump" kidney. J Anat 2001; 198:501-4.  Back to cited text no. 5

Correspondence Address:
Leonardo Spatola
Department of Internal Medicine, "San Pellegrino" Hospital, Castiglione delle Stiviere, MN
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/1319-2442.198277

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  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7]


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