Indian Journal of Urology Users online:1436  
IJU
Home Current Issue Ahead of print Editorial Board Archives Symposia Guidelines Subscriptions Login 
Print this page  Email this page Small font sizeDefault font sizeIncrease font size


 
  Table of Contents 
CASE REPORT
Year : 2013  |  Volume : 29  |  Issue : 1  |  Page : 53-55
 

Metanephric stromal tumour: A rare pediatric benign stromal specific renal neoplasm


1 Department of General Pathology, Christian Medical College and Hospital, Vellore, Tamilnadu, India
2 Department of Pediatric Surgery, Christian Medical College and Hospital, Vellore, Tamilnadu, India

Date of Web Publication3-Apr-2013

Correspondence Address:
Seema D Khutti
Department of General Pathology, 84-10 Main Street, Apartment - 457, Briarwood, New York - 11435, United States America

Login to access the Email id

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0970-1591.109985

Rights and Permissions

 
   Abstract 

A case of incidentally detected Metanephric Stromal Tumour (MST) is reported here. This is a rare, recently recognized pediatric benign stromal specific renal neoplasm. A review of the English literature revealed only five cases after its original description by Argani et al. Recognition of this entity can spare a child from potentially toxic adjuvant chemotherapy that might be used to treat malignant lesions which are part of the differential diagnosis, particularly clear cell sarcoma of kidney (CCSK).


Keywords: Clear cell sarcoma, kidney, metanephric stromal tumour


How to cite this article:
Khutti SD, Kumar RP, Sampath K. Metanephric stromal tumour: A rare pediatric benign stromal specific renal neoplasm. Indian J Urol 2013;29:53-5

How to cite this URL:
Khutti SD, Kumar RP, Sampath K. Metanephric stromal tumour: A rare pediatric benign stromal specific renal neoplasm. Indian J Urol [serial online] 2013 [cited 2019 Jul 18];29:53-5. Available from: http://www.indianjurol.com/text.asp?2013/29/1/53/109985



   Introduction Top


Metanephric Stromal Tumour (MST), first described in 2000 by Argani et al., [1] is a rare, purely stromal specific renal neoplasm that mainly affects children. Its characteristic microscopic appearance and immunohistochemical profile helps to differentiate it from congenital mesoblastic nephroma (CMN) and clear cell clear cell sarcoma of kidney (CCSK). Since then, there have been only five case reports of this tumour in the English literature. Its recognition is essential as it spares the patient from unnecessary potentially toxic adjuvant chemotherapy. A case of paediatric metanephric stromal tumour is described and the clinical presentation, radiological and pathological findings, differential diagnoses and biological behaviour are discussed.


   Case Report Top


A three year old boy presented with a complaint of dribbling of urine. He had one episode of hematuria at two years of age but no other complaints such as abdominal pain, fever, loss of appetite or weight loss. On systemic examination, there were no palpable masses or any other abnormalities. As part of the initial work up, an ultrasonography of abdomen was performed, this showed a partly exophytic hypo-echoic mass arising from the interpolar region, measuring 4.7 × 4.8 × 5.3 cm. Vascularity was noted within the mass, suggestive of Wilm's tumour. Ultrasound guided biopsy of the renal mass was performed, which on microscopic examination showed a tumour composed of sheets of spindle shaped cells with oval to elongated nuclei and moderate amounts of cytoplasm. There was no obvious atypia or any other feature of malignancy. Occasional tubules were noted, lined by cuboidal cells. The biopsy was reported as a spindle cell lesion with occasional tubular structures. The cells were negative for WT-1 and S-100 on immunohistochemistry. Based on the biopsy report and the radiological findings, the patient underwent nephroureterectomy. The operation was uneventful and the patient recovered appropriately.

A kidney measuring nine cm in maximum dimension was received in the laboratory. The external surface was smooth. Sectioning revealed a firm white tumour, 7.5 × 5.5 × 4.5 cm replacing most of the kidney. There were a few small cystic areas containing serous fluid. The neoplasm appeared to abut the pelvis but there was no infiltration into pelvic or perirenal fat [Figure 1]. Microscopically the tumour had a slightly nodular architecture due to varying cellularity and was composed of spindle cells with thin tapered bland nuclei an indistinct cytoplasm [Figure 2]. Focally, a concentric arrangement around entrapped tubules and vessels, imparting 'the onion skin' morphology, was noted [Figure 3]. A few entrapped glomeruli were also present. The tumour was well demarcated from the adjacent kidney, but without a definite capsule [Figure 4]. Some blood vessels showed hypercellularity around the endothelium with thickened walls but there were no features of dysplasia [Figure 5]. Mitotic activity and necrosis were absent. There was no evidence of capsular or vascular invasion, heterologous differentiation or neoplastic epithelium. There were no nephrogenic rests either. On immunohistochemistry, the cells were positive for Vimentin, focally positive for CD-34 [Figure 6] and negative for WT-1, Desmin and Smooth muscle actin. The entrapped tubules showed positivity for Cytokeratin. These findings were consistent with MST. Patient's initial complaint of 'dribbling of urine' subsided after undergoing nephroureterectomy. Patient had come for follow-up after six months of operation. Ultra-sound done during this visit showed no local recurrence.
Figure 1: Gross Pathological Findings: Cut surface of the kidney shows that the tumour was fi rm grey white, 7.5 × 5.5 × 4.5 cm in size, replacing most of the kidney

Click here to view
Figure 2: Microphotograph of neoplasm showing slightly nodular architecture due to varying cellularity and was composed of spindle cells with thin tapered bland nuclei an indistinct cytoplasm (hematoxylin and eosin stain, ×100)

Click here to view
Figure 3: Microphotograph of neoplasm showing concentric arrangement around entrapped tubules, imparting 'onion skin appearance' (hematoxylin and eosin stain, ×200)

Click here to view
Figure 4: Microphotograph of neoplasm showing well demarcation from the adjacent kidney but without a defi nite capsule (hematoxylin and eosin stain, ×200)

Click here to view
Figure 5: Microphotograph of neoplasm showing blood vessels having hypercellularity around endothelium with thickened walls but there were no features of dysplasia (H and E stain, ×200)

Click here to view
Figure 6: Immunohistochemical staining for CD 34 showing focal positivity (×200)

Click here to view



   Discussion Top


The origin of MST is not entirely clear, but it is thought to be related to Wilm's Tumour, unlike other renal stromal tumours such as CMN, CCSK and rhabdoid tumour of kidney (RTK). Beckwith has postulated that MST may represent the result of maturation of intralobar nephrogenic rests (INR) with the loss of any active blastemal component. [1],[2] Characteristic histological features of MST include (a) alternating cellularity that imparts a nodular low power appearance (b) onion skin cuffing around entrapped renal tubules (c) heterologous differentiation and vascular alterations (d) juxta glomerular cell hyperplasia and (e) patchy positivity of tumour cells for CD 34, though variable. The last three features are not present in all the cases. [1],[2],[3],[4] Our case did not show heterologous differentiation, angiodysplasia of the vessel wall or juxta glomerular cell hyperplasia. However, the other histological features and patchy positivity for CD34 and negativity for Desmin helped to exclude other neoplasms in the differential diagnosis. MST is differentiated from CMN by its scalloped, subtly infiltrative border, in contrast with the deeply invasive nature of most CMN. Also MST stains for CD34, while CMN is reported to be positive for Desmin. Clinically, patients of MST are older than the known upper limit for those with CMN (CMN is usually a tumour of infancy). MST can be differentiated from CCSK by the regular branching capillary vascular pattern which is characteristic of CCSK but absent in MST. Also, CCSK are uniformly negative for CD34 and S-100. The distinction between MST and metanephric adenofibroma (MAF) was possible due to the absence of discrete epithelial nodules, more characteristic of MAF. [1],[4] The most common presentation as described by Argani et al. [1] is an abdominal mass followed by hematuria, recurrent urinary tract infection (UTI), incontinence, fever, anemia and hypertension. [5] Our patient presented with the complaint of dribbling of urine. As part of the initial work up, ultrasound of the abdomen was performed, revealing a hypo echoic mass arising from the interpole of kidney. MST is a benign tumour that is centered in medulla, but, in one case continous extension through bladder into the prostatic urethra has been reported. The maximum diameter of our tumour was 7.5 cm. Only three cases, out of the thirty one cases described by Argani et al. [1] had a maximum dimension greater than 7.5 cm, the largest in his series measuring 10 cm. None of the five cases reported thereafter [Table 1] were larger than 5.5 cm in diameter. MST mainly affects children; Mc Donald OG et al. [5] and Langer BR et al. [6] have described adult presentations of MST. Most MSTs were previously classified as congenital mesoblastic nephroma until recently, when Beckwith and others re-characterized this neoplasm after reviewing the files of the National Wilm's Tumour Study Pathology Centre. We agree that treatment of these patients should continue to be nephrectomy. An accurate radiological diagnosis is impossible and the role of partial nephrectomy is unclear at this time. At present, all clinical MST should be fully excised in order to establish a definitive diagnosis. Once the diagnosis is confirmed, no further adjuvant therapy is required. Thorough evaluation by an experienced pathologist is essential for the correct diagnosis.
Table 1: Summary of the 5 cases of Metanephric Stromal Tumour described in the literature after the report of Argani et al.: [2-6]

Click here to view


 
   References Top

1.Argani P, Beckwith JB. Metanephric stromal tumour: Report of 31 cases of a distinctive pediatric renal neoplasm. Am J Surg Pathol 2000;24:917-26.  Back to cited text no. 1
    
2.Lorenzo AJ, Timmons C, Weinberg A, Megison SM, Snodgrass WT, et al. Metanephric stromal tumour with urothelial extension. J Urol 2003;169:1095-7.  Back to cited text no. 2
    
3.Palese MA, Ferrer F, Perlman E, Gearhart JP, et al. Metanephric stromal tumour: A rare benign pedatric renal mass. Urology 2001;462:15-8.  Back to cited text no. 3
    
4.Rajlakshmi V, Chandran P, Selvambigai, Ganesh J, et al. Metanephric stromal tumour: A novel pediatric renal neoplasm. Indian J Pathol Microbiol 2009;52:389-91  Back to cited text no. 4
    
5.McDonald OG, Rodriguez R, Bergner A, Argani P, et al.Metanephric stromal tumour arising in a patient with neurofibromatosis type 1 syndrome. Int J Surg Pathol 2011;19:667-71  Back to cited text no. 5
    
6.Bluebond-Langner R, Pinto PA, Argani P, Chan TY, Halushka M, Jarrett TW, et al. Adult presentation of metanephric stromal tumour. J Urol 2002;168:1482-3.  Back to cited text no. 6
    


    Figures

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

  [Table 1]



 

Top
Print this article  Email this article
 

    

 
   Search
 
  
    Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
    Article in PDF (4,066 KB)
    Citation Manager
    Access Statistics
    Reader Comments
    Email Alert *
    Add to My List *
* Registration required (free)  


    Abstract
   Introduction
   Case Report
   Discussion
    References
    Article Figures
    Article Tables

 Article Access Statistics
    Viewed2372    
    Printed41    
    Emailed1    
    PDF Downloaded49    
    Comments [Add]    

Recommend this journal

HEALTHWARE INDIA