British Journal of Radiology (2004) 77, 436-437
© 2004 British Institute of Radiology
doi: 10.1259/bjr/42350647
Cellular congenital mesoblastic nephroma with contralateral medullary nephrocalcinosis
A Ozturk, MD
1
M Haliloglu, MD
1
E Akpinar, MD
1 and
S Tekgul, MD
2
Departments of 1 Radiology and 2 Urology, Hacettepe University Faculty of Medicine, 06100 Ankara, Turkey
Correspondence: Dr Mithat Haliloglu, Simon Bolivar Cad. 14/47, Cankaya, 06550 Ankara, Turkey
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Abstract
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Congenital mesoblastic nephroma is the most common renal mass in the newborn period and can present with atypical findings. Certain associated conditions such as hypercalcaemia, hypertension and reninism have been described. We report a cellular variant of congenital mesoblastic nephroma with hypercalcaemia and contralateral medullary nephrocalcinosis.
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Introduction
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Congenital mesoblastic nephroma (CMN) is a rare benign congenital renal tumour in children but is the most common renal tumour under the age of 6 months, accounting for almost half of renal tumours in this age group. CMN was first described by Bolande as a unique renal tumour distinct from Wilms tumour [1]. A pathological spectrum, which ranges from the benign typical CMN to the malignant spindle cell variety, has been previously described. The cellular variant of CMN has a less favourable prognosis, primarily occurring in infants over 3 months of age. CMN has been reported to be associated with hypercalcaemia, hypertension, reninism and other examples of ectopic hormone production [2–4]. We report a case of congenital mesoblastic nephroma associated with hypercalcaemia and contralateral medullary nephrocalcinosis.
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Case report
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A 1-month-old boy was transferred from another hospital after presenting with abdominal discomfort, urinary infection and a right-sided abdominal mass. On physical examination, a large abdominal mass was palpated in the right side of the abdomen. Laboratory investigations revealed haematuria and mild hypercalcaemia (11.4 mg dl–1, normal 8.6–10.2 mg dl–1). Abdominal ultrasound revealed an 11 cm complex abdominal mass in the right retroperitoneal space, composed of large cystic areas, interspersed with solid material. The medullary pyramids of the left kidney were echogenic consistent with medullary nephrocalcinosis (Figure 1
). MRI of the abdomen showed a heterogeneous solid mass composed of cystic, necrotic and haemorrhagic areas. The remaining normal right kidney was displaced anteromedially (Figure 2). Right nephrectomy was performed. Histopathological analysis of the surgical specimen revealed a cellular variant of CMN. The serum calcium remained normal after nephrectomy (8.8 mg dl–1).
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Figure 1. Ultrasound of the left kidney shows echogenic medullary pyramids consistent with medullary nephrocalcinosis.
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Figure 2. (a) T2 weighted coronal MR image demonstrates the heterogeneous appearance of the mass. The remaining kidney is compressed and displaced anteromedially (arrow). (b) Contrast enhanced T1 weighted axial MR image shows heterogeneously enhanced large mass containing necrotic areas. Note the remainder of the right kidney is displaced anteromedially.
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Discussion
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CMN is a rare benign congenital renal tumour in children. It is often present at birth and the mean age of presentation is 3 months. Certain associated conditions such as hypercalcaemia, hypertension, reninism and other examples of ectopic hormone production have been described [2–4].
The pathological spectrum ranges from the benign typical conventional CMN to the subgroup with highly cellular histology that may increase the malignant potential. The cellular variant of CMN, primarily occurring in infants over 3 months of age, has a less favourable prognosis because local recurrence or metastases may occur [5]. Nephrectomy is the recommended therapy. The tumour in our case exhibited necrosis, dense cellularity and high mitotic activity, which are hallmarks of this more aggressive variant.
Imaging is important in CMN, for assessing local invasion by tumour prior to surgery and also following up these patients for local recurrence. Radiological findings of CMN are non-specific. Differentiation of these benign tumours from Wilms tumour is not possible without pathological examination. Ultrasound, CT and MRI establish the renal origin of a solid mass with irregular cystic and haemorrhagic areas. Radiographs demonstrate a large soft tissue mass that rarely calcifies [5].
Medullary nephrocalcinosis has been described pathologically as calcium phosphate or calcium oxalate deposits involving the distal convoluted tubules in the loop of Henle. It can be recognized as multiple, small, medullary calcifications. Usually this abnormality results from a metabolic disturbance and is common with hypercalcaemic states [6].
Hypercalcaemia is an uncommon finding in childhood renal tumours. In Leblanc's study only 17 cases with hypercalcaemia were discovered among 2400 paediatric solid tumours and only 4 were of renal origin [7]. An extensive review of literature reveals that only 14 reported cases of renal tumours in children were associated with hypercalcaemia [8]. Eight patients out of 14 had malignant rhabdoid tumour of kidney and six had CMN. The mechanism of hypercalcaemia is believed to be a result of secretion of parathyroidhormone (PTH), PTH-related peptide [9] or prostaglandine E2 [8]. There are no reported cases of hypercalcaemia associated with Wilms tumour and clear sarcoma of kidney [8].
A case of CMN co-occurring with hypercalcaemia and contralateral medullary nephrocalcinosis has been published before [3]. In this case, medullary nephrocalcinosis was shown in both the contralateral normal kidney and the kidney with CMN. In our case, medullary nephrocalcinosis was present only in the normal left kidney. Since almost the entire right kidney was replaced by the mass, there was no evidence of medullary nephrocalcinosis of the remaining part.
In conclusion, we suggest that radiological evidence of nephrocalcinosis in the ipsilateral or contralateral kidney could be a means of differentiating CMN from other renal tumours of newborn period, especially Wilms tumour although it is rare in the neonate.
Received for publication January 29, 2003.
Revision received July 2, 2003.
Accepted for publication August 20, 2003.
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References
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- Bolande RP, Brough AJ, Izant RJ. Congenital mesoblastic nephroma of infancy: a report of eight cases and relationship to Wilms' tumor. Pediatrics 1967;40:272–8.[Abstract/Free Full Text]
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Abstract
Introduction
