British Journal of Radiology (2008) 81, e35-e36
© 2008 British Institute of Radiology
doi: 10.1259/bjr/26082288
Milk of calcium collection in the differential diagnosis of giant renal calculus
S ULUSAN, MD
and
Z KOC, MD
Baskent University Faculty of Medicine, Department of Radiology, Adana Teaching and Medical Research Center, Yuregir, Adana, Turkey
Correspondence: Serife Ulusan, MD, Baskent University Faculty of Medicine, Department of Radiology, Adana Teaching and Medical Research Center, Dadaloglu Mah. 39 Sok. No:6, 01250, Yuregir, Adana, Turkey. E-mail: sulusan{at}hotmail.com
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Abstract
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A 29-year-old man presented with milk of calcium that completely filled the right-sided renal collecting system and ureter and was thought to be a giant renal calculus. Plain radiographs and computed tomographic findings of this rarity, which has not been reported previously, are reviewed.
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Introduction
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Renal milk of calcium contains a colloidal suspension of calcium crystals. In most cases, the specific radiological findings of this entity include the changing shape of an intrarenal opacity noted when the patient is between the supine and upright positions and a calcific suspension showing fluid–fluid levels and a half-moon contour when plain abdominal radiographs are taken of the patient in the erect position [1].
Giant renal calculi (kidney stones weighing more than 500 g) have been reported rarely in the literature. If no obstruction is present, some renal calculi can enlarge to a huge size without causing severe symptoms. To our knowledge, only seven cases of giant renal calculi have been reported in the literature [2]. The aim of this report was to show that the radiological findings of milk of calcium that fills the renal collecting system and ureter differ from those considered typical.
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Case report
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A 29-year-old man who was undergoing haemodialysis for chronic renal failure was admitted to our urology clinic for the treatment of right-sided flank pain. The results of physical examination and haematological and biochemical analyses were within normal limits. Plain radiographs obtained with the patient in the supine and erect positions showed giant right-sided renal hyperdense material without fluid–fluid levels. The hyperdense material appeared to fill the collecting system and two-thirds of the proximal ureter (Figure 1
). Non-contrast computed tomographic findings confirmed that the collecting system of the right kidney and two-thirds of the proximal ureter were filled with a hyperdense material and had an extremely thin renal parenchyma (Figure 2). This material was thought to be a giant renal calculus (8 cmx 6 cm) and a giant ureteral stone (15 cmx 2 cm).
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Figure 1. A plain radiograph obtained with the patient in the erect position showing the right-sided collecting system and ureter filled with milk of calcium without fluid–fluid levels.
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Figure 2. A coronal multiplanar reconstruction computed tomographic image shows that the collecting system and ureter are filled with milk of calcium on the right side.
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Because the patient had severe flank pain that was not responsive to the analgesics, simple right-sided nephrectomy and ureterectomy was performed through a subcostal extraperitoneal flank incision. At surgery, right-sided hydronephrosis and hydroureter were identified, and the right kidney and ureter were excised. On macroscopic examination, the right-sided collecting system and ureter were found to be filled with a greyish substance that resembled paste, and the kidney was noted to be atrophic. Microscopic examination revealed a colloidal suspension of calcium crystals that proved to be milk of calcium.
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Discussion
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The cause of the formation of milk of calcium has not been established, although a disturbance in the balance between stone-forming factors and inhibitors of stone formation has been proposed as the primary cause. Hydronephrosis with or without infection can also lead to the formation of a milk of calcium collection [3]. In our case, the typical milk of calcium changes in position on imaging were not observed, because the milk of calcium was concentrated and completely filled the affected collecting system. Although the images suggest that there is an obstructing calculus in the right ureter, calculus was not seen during either surgery or pathological examination. Therefore, we thought that the cause of accumulation of the milk of calcium in the right renal collecting system may be related to a stenosis at the exaggerated second points of narrowness of the right ureter, where the ureter crosses the external iliac or terminal iliac artery at the pelvic rim.
We believe that this was the case in our patient, in whom obstruction of the distal ureter might have caused the formation of milk of calcium. A milk of calcium renal cyst was first reported by Ludin and Howald [4] in 1940. Milk of calcium has been previously reported to occur in calycine diverticula [5], in a ureter or in a ureterocele [6]. However, to our knowledge, milk of calcium that completely filled the collecting system and ureter has not been reported in the literature.
We considered autonephrectomy after tuberculosis infection of the urinary tract in the differential diagnosis. In tuberculosis of the urinary tract the collecting system and ureter can be filled with calcified caseating material proximal to the ureteric stricture, producing a similar appearance to our reported case [7]. Clinical and laboratory findings suggested tuberculosis was not observed in our case.
Even if we had known preoperatively that milk of calcium was the substance within the collecting system and ureter, our patient's surgical management would have remained unchanged because of his having to undergo haemodialysis. However, milk of calcium can also develop in individuals without renal failure or in those with only one kidney.
Despite the rarity of milk of calcium in the collecting system and ureter, this condition should be considered in the differential diagnosis of a giant renal calculus. Our case is significant because it is to our knowledge the first report in which milk of calcium that completely filled the collecting system and ureter has been described and also because in our patient the presentation of a milk of calcium collection differed from that considered typical.
Received for publication April 11, 2006.
Revision received October 4, 2006.
Accepted for publication November 20, 2006.
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References
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- Melekos MD, Kosti PN, Zarakovitis IE, Dimopoulos PA. Milk of calcium cysts masquerading as renal calculi. Eur J Radiol 1998;28:62–6.[CrossRef][Medline]
- Ludin M, Howald R. Eine eigenartige intrarenale Zyste. Schweiz med Wochenschr 1940;70:276–8.
- Healey T, Way BG, Grundy WR. Milk of calcium in calycine diverticula. Br J Radiol 1980;53:845–52.[Abstract/Free Full Text]
- Lieb J, Abrahams HM, Das AK. Endoscopic management of milk of calcium-filled ureterocele stump. J Endourol 2003;17:917–18.[CrossRef][Medline]
- Engin G, Acunas B, Acunas G, Tunaci M. Imaging of extrapulmonary tuberculosis. RadioGraphics 2000;20:471–88.[Abstract/Free Full Text]
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Abstract
Introduction
