Figure 1
Right kidney
Axial sonogram showing replacement of the right kidney by a multi-loculated cystic mass
Mesoblastic nephroma
SectionPaediatric radiology
Case TypeClinical Cases
AuthorsJP Reaney, A Paterson
Connected authors
4 weeks, female
Clinical History
Born at 36 weeks gestation via emergency caesarean section. A right-sided abdominal mass was noted on physical examination. The patient was clinically hypertensive and subsequently developed severe hypercalcaemia with a peak corrected Calcium of 4.26mmol/L. An abdominal ultrasound examination was performed.
Imaging Findings
Ultrasound demonstrated replacement of the right kidney by a multi-loculated cystic mass, which measured approximately 6.5 x 7.0 cm in the transverse plane. The mass was seen to arise from the upper pole of the kidney, with the lower pole having a more normal sonographic appearance. Due to the hypertension being difficult to manage, and the elevated calcium not responding to medical therapy, an abdominal CT examination was requested to further evaluate the mass. This demonstrated a large, mixed attenuation mass arising from the upper pole of the right kidney, which contained fluid-filled locules. No calcification was seen. There was no vessel encasement or evidence of distant metastases.
The patient proceeded to have a right radical nephrectomy at one month of age. Pathology confirmed a mesoblastic nephroma. Post-operatively, the hypertension resolved and the corrected calcium had returned to normal levels by the time of discharge.
The patient proceeded to have a right radical nephrectomy at one month of age. Pathology confirmed a mesoblastic nephroma. Post-operatively, the hypertension resolved and the corrected calcium had returned to normal levels by the time of discharge.
Discussion
Congenital mesoblastic nephroma (CMN) is the most common renal tumour in infants less than 1-year-of-age [1, 2]. The majority present with a palpable mass on abdominal examination [2]. Less often, haematuria, hypertension, vomiting and anaemia are seen [3]. A renal mass may be identified on prenatal US, in association with polyhydraminos, hydrops and premature delivery [1, 2]. Hypercalcaemia may be detected in up to 20% of case; the biochemical mechanism is unknown [4].
CMN exists as a spectrum from the classically benign to the aggressive cellular subtype [1]. Typically, the classic variant presents in the first 3 months of life with a predominantly solid, non-agressive tumour [3]. Cellular CMN usually presents later, and is more aggressive [3], being larger in size, with areas of haemorrhage, cystic change and necrosis [3].
There are no pathognomic imaging findings for CMN [3]. Ultrasound is the initial invesitgation of choice and the findings vary from the predominantly solid classic CMN, to a largely cystic tumour in the cellular subtype [3]. On contrast-enhanced CT, there is minimal (mainly peripheral) enhancement of the solid components in classic CMN tumour, but more focal enhancement may be seen in cellular CMN tumours [1, 3]. Imaging features that distinguish the cellular from the classic subtype include vascular encasement and intraspinal extension [4]. MRI findings are variable, with one series reporting low signal tumours on T1 with focal areas of T1 shortening due to haemorrhage [1].
The differential diagnosis includes both renal and non renal tumours. Wilms tumour is the most common renal tumour in children, but <2% are diagnosed below 3-months-of-age [1, 3]. Multilocular cystic nephroma has similar imaging characteristics to cystic CMN, making it difficult to differentiate between them. Other rarer renal neoplasms include clear-cell carcinoma and aggressive rhabdoid tumours, but unlike CMN these often have metastatic disease at time of diagnosis [1, 3]. Neuroblastoma arising from the adjacent adrenal gland is the main nonrenal differential diagnosis [1].
Radical nephrectomy with negative margins is the main treatment for CMN and is usually curative [3, 4]. Due to the infiltrative behaviour and absence of a tumour capsule, partial nephrectomy is not advised [3, 4]. Further treatment is usually not required [3].
The rate of relapse is approximately 10% within the first year, seen predominantly with cellular CMN [3]. Relapse is local in >50% of cases or metastatic, to the lungs, heart, liver, brain or bones [3, 4]. Treatment options for recurrence include surgical resection, salvage chemotherapy and radiotherapy [3].
CMN exists as a spectrum from the classically benign to the aggressive cellular subtype [1]. Typically, the classic variant presents in the first 3 months of life with a predominantly solid, non-agressive tumour [3]. Cellular CMN usually presents later, and is more aggressive [3], being larger in size, with areas of haemorrhage, cystic change and necrosis [3].
There are no pathognomic imaging findings for CMN [3]. Ultrasound is the initial invesitgation of choice and the findings vary from the predominantly solid classic CMN, to a largely cystic tumour in the cellular subtype [3]. On contrast-enhanced CT, there is minimal (mainly peripheral) enhancement of the solid components in classic CMN tumour, but more focal enhancement may be seen in cellular CMN tumours [1, 3]. Imaging features that distinguish the cellular from the classic subtype include vascular encasement and intraspinal extension [4]. MRI findings are variable, with one series reporting low signal tumours on T1 with focal areas of T1 shortening due to haemorrhage [1].
The differential diagnosis includes both renal and non renal tumours. Wilms tumour is the most common renal tumour in children, but <2% are diagnosed below 3-months-of-age [1, 3]. Multilocular cystic nephroma has similar imaging characteristics to cystic CMN, making it difficult to differentiate between them. Other rarer renal neoplasms include clear-cell carcinoma and aggressive rhabdoid tumours, but unlike CMN these often have metastatic disease at time of diagnosis [1, 3]. Neuroblastoma arising from the adjacent adrenal gland is the main nonrenal differential diagnosis [1].
Radical nephrectomy with negative margins is the main treatment for CMN and is usually curative [3, 4]. Due to the infiltrative behaviour and absence of a tumour capsule, partial nephrectomy is not advised [3, 4]. Further treatment is usually not required [3].
The rate of relapse is approximately 10% within the first year, seen predominantly with cellular CMN [3]. Relapse is local in >50% of cases or metastatic, to the lungs, heart, liver, brain or bones [3, 4]. Treatment options for recurrence include surgical resection, salvage chemotherapy and radiotherapy [3].
Differential Diagnosis List
Congenital mesoblastic nephroma
Wilm\'s tumour
Multilocular cystic nephroma
Clear cell carcinoma
Neuroblastoma of adrenal gland
Final Diagnosis
Congenital mesoblastic nephroma
References
[1] 1. Chaudry G, Perez-Atayde AR, Ngan BY, Gundogan M, Daneman A (2009) Imaging of congenital mesoblastic nephroma with pathological correlation. Pediatr Radiol 39(10): 1080-1086 (PMID: 19629463)
[2] 2. Lowe LH, Isuani BH, Heller RM, Stein SM, Johnson JE, Navarro OM, Heranz-Schulman M (2000) Pediatric renal masses: Wilms tumor and beyond. RadioGraphics 20(6):1585–1603 (PMID: 11112813)
[3] 3. Sheth MM, Cai G, Goodman TR (2012) AIRP best cases in radiologic-pathologic correlation: congenital mesoblastic nephroma. RadioGraphics 32(1):99-103 (PMID: 22236896)
[4] 4. Bayindir P, Guillerman RP, Hicks MJ, Chintagumpala MM (2009) Cellular mesoblastic nephroma (infantile renal fibrosarcoma): institutional review of the clinical, diagnostic imaging, and pathologic features of a distinctive neoplasm of infancy. Pediatr Radiol 39(10): 1066-1074 (PMID: 19629465)
Case information
| URL: | https://www.eurorad.org/case/10949 |
| DOI: | 10.1594/EURORAD/CASE.10949 |
| ISSN: | 1563-4086 |
Figure 2
Right kidney
Axial CT demonstrating a large, mixed attenuation mass arising from the upper pole of the right kidney, containing fluid-filled locules. No calcification was seen.
Right kidney
Axial sonogram showing replacement of the right kidney by a multi-loculated cystic mass
Radiology Dept, Royal Belfast Hospital for Sick Children, Belfast, Northern Ireland
Radiology Dept, Royal Belfast Hospital for Sick Children, Belfast, Northern Ireland
Right kidney
Axial CT demonstrating a large, mixed attenuation mass arising from the upper pole of the right kidney, containing fluid-filled locules. No calcification was seen.
Radiology Dept, Royal Belfast Hospital for Sick Children
Radiology Dept, Royal Belfast Hospital for Sick Children