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Table of Contents
CASE REPORT
Year : 2016  |  Volume : 8  |  Issue : 1  |  Page : 114-117  

Peritoneal seeding following incomplete resection of mixed epithelial stromal tumor of the kidney: First case report


1 Department of Urology, University of Arkansas Medical Sciences, Little Rock, Arkansas, USA, USA
2 Department of General Surgery, University of Arkansas Medical Sciences, Little Rock, Arkansas, USA
3 Department of Pathology, University of Arkansas Medical Sciences, Little Rock, Arkansas, USA
4 Department of Urology, University of Arkansas Medical Sciences, Little Rock, Arkansas, USA

Date of Submission04-Aug-2015
Date of Acceptance11-Dec-2015
Date of Web Publication10-Dec-2015

Correspondence Address:
Mohamed H Kamel
University of Arkansas for Medical Sciences, 4301 W Markham St. #540, Little Rock, AR 72205
USA
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DOI: 10.4103/0974-7796.171493

PMID: 26834418

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   Abstract 

Mixed epithelial stromal tumor (MEST) is rare and typically benign renal cystic neoplasm that cannot be clinically distinguished from cystic renal cell carcinoma. Its mainstay course of diagnosis and treatment remains surgical excision. Recurrence and malignant transformation is rare but has previously been described. To our best knowledge, we present the first case of peritoneal seeding resulting in a paracolonic MEST following incomplete resection in a patient with benign MEST. This signifies a new pathological behavior for MEST, predominantly, a benign kidney tumor. In addition, documentation with more cases of MEST is needed to further understand its pathogenesis, clinical behavior, malignant potential, and optimal management.

Keywords: Adult mesoblastic nephroma, benign kidney tumor, benign renal cyst, cystic nephroma, mixed epithelial stroma tumor, mixed epithelial stromal tumor, paracolonic cyst, recurrence


How to cite this article:
Farias JA, Laryea J, Gokden N, Kamel MH. Peritoneal seeding following incomplete resection of mixed epithelial stromal tumor of the kidney: First case report. Urol Ann 2016;8:114-7

How to cite this URL:
Farias JA, Laryea J, Gokden N, Kamel MH. Peritoneal seeding following incomplete resection of mixed epithelial stromal tumor of the kidney: First case report. Urol Ann [serial online] 2016 [cited 2021 Nov 28];8:114-7. Available from: https://www.urologyannals.com/text.asp?2016/8/1/114/171493


   Introduction Top


Mixed Epithelial Stromal Tumor (MEST) is a rare and typically benign renal cystic neoplasm. It was first described as its own entity by Michal et al. in 1998, differing from other renal tumors of epithelial and mesenchymal differentiation.[1] Histologically, it is a distinctive tumor characterized by its biphasic pattern composed of varied epithelial elements that form glands and cysts embedded within proliferative spindle cell, ovarian-like stroma staining positive for estrogen and progesterone receptors.[2] Previous terminology includes adult mesoblastic nephroma, leiomyomatous renal hamartoma, solid and cystic biphasic tumor, cystic hamartoma, and adult metanephric stromal tumor.[3] Classic presentation is that of a middle aged peri-menopausal female with history of long term estrogen therapy. Macroscopic features include a mass with solid and cystic components, usually centrally located that may herniate into the pelicalviceal collecting system. On CT imaging, it is a well-circumscribed multiseptate cystic and solid mass with delayed contrast material enhancement often categorized as a Bozniak III or IV cyst.[4] The differential diagnosis is extensive and includes angiomyolipoma with cysts, synovial sarcoma of kidney, sarcomatoid carcinoma, leiyomyosarcoma, mulitcystic dysplastic kidney, obstructed duplicated renal system, renal abscess, and multilocular cystic renal cell carcinoma (RCC).[4],[5] Since MEST cannot be clinically distinguished from cystic renal cell carcinoma, surgical excision is the mainstay course for definitive diagnosis and treatment. Although considered a benign tumor, MEST can have malignant transformation with recurrence as previously reported.[6],[7],[8],[9],[10] To our best knowledge, we present the first case of peritoneal seeding resulting in a paracolonic MEST following incomplete resection in a patient with benign MEST.


   Case Report Top


The patient is a 38-year-old Caucasian female, who presented with right flank pain. She denied any gross hematuria or history of urinary tract infections. Her past medical history was significant for hypertension and polycystic ovarian syndrome on metformin. She was a nonsmoker and had no family history of genitourinary diseases. She had no history of hormonal therapy. A computed tomography (CT) scan of the abdomen and pelvis renal mass protocol showed a 9 cm mass with fluid density and very thin intracystic septations representing a Bosniak II cyst in her right kidney [Figure 1]. Due to flank pain resulting in multiple visits to the emergency room, the patient elected surgical treatment. She underwent robotic-assisted renal cyst marsupialization via transperitoneal approach and tolerated the procedure well with an uneventful postoperative course. Her surgical pathology showed mixed epithelial stromal tumor (MEST) measuring 6 cm in maximum dimension and focally present at the cauterized edge. She was seen at a 3-week postoperative visit. Although she had a positive margin, the plan was to return in 1 year with repeat imaging owing to the benign nature of this disease. However, she was lost to follow-up and presented 3 years later with a CT scan showing an 11 cm × 8 cm right renal cystic lesion with few thin internal septations and focal punctate calcifications along the walls of the cyst. Interestingly, she was also found to have multiple cystic lesions near the ascending colon with similar radiologic features as the renal cyst suspicious for MEST deposits [Figure 2]. She was referred to colorectal surgery, and a colonoscopy was performed that did not show any intraluminal abnormalities. Due to recurrence and fear of malignancy, the patient underwent a hand-assisted laparoscopic radical nephrectomy by urology team. Then she underwent an excision of cystic multiloculated mesenteric lesion that was attached to the ascending colon [Figure 3] by the colorectal team using Endo GIA™ stapler. Final surgical pathology showed MEST in the right kidney and also in the paracolonic mass. The patient was discharged on postoperative day 2 with no issues.
Figure 1: Initial 9 cm right renal cyst

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Figure 2: Paracolonic cystic lesion (white arrow) along the ascending colon in relation to recurrent right renal mixed epithelial stromal tumor cyst (red arrow)

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Figure 3: Mesenteric multiloculated paracolonic mixed epithelial stromal tumor lesion (arrows)

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Pathology

The multiloculated cystic lesion showed epithelial and stromal components. Most cysts were lined by flat to cuboidal and in some areas with hobnailed epithelium. No atypia is present in the epithelial component. The stroma was composed of areas of dense fibrous, loose, smooth muscle, hypercellular spindled, and ovarian stroma-like elements [Figure 4]. No mitotic activity or atypia was observed in those stromal components either. The septae did not contain any normal renal parenchyma.
Figure 4: H and E stain of the renal cyst showing dense fibrous, loose, smooth muscle, hypercellular spindled, and ovarian stroma-like elements (×40)

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Immunohistochemistry

Stromal cells showed diffuse nuclear estrogen and progesterone positivity, consistent with MEST or also known as cystic nephroma [Figure 5].
Figure 5: Immunohistochemical stain of stroma is positive for estrogen receptor (×200)

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   Discussion Top


There appears to be approximately around 100 cases of MEST reported in the literature.[11] Due to its rare occurrence and recent recognition as a distinct tumor, it is not very well understood. A hormonal mechanism for MEST's pathogenesis has been postulated secondary to the female predilection, association with hormonal use, and estrogen/progesterone positivity.[2] Pathologically, the differential diagnosis includes multilocular cystic renal cell carcinoma, tubulocystic carcinoma, cystic partially differentiated nephroblastoma, and metanephric adenofibroma. Clinically, it cannot be distinguished from other renal cystic lesions and should be considered as high on the differential diagnosis in a middle-aged female patient with a history of hormone therapy. A nephron sparing approach is encouraged even for large masses compressing the collecting system.[12] In our patient, we did not obtain a complete negative margin at the time of her initial surgery. Owing to the perceived benign nature of MEST, we elected for active surveillance with periodic imaging. However, due to the rapid rate of her recurrence and fear of malignancy, we elected to perform radical nephrectomy and excision of the paracolonic mass. Recently, a similar case has been reported in the literature in a female patient treated with robotic decortication for a complex cystic mass that recurred 2 years later, which was then treated with nephrectomy and found to have benign MEST.[13] To our best knowledge, we present the first case of local recurrence with benign MEST of kidney and peritoneal seeding resulting in a paracolonic MEST. Seeding of cells into the peritoneal cavity following incomplete resection represents a new pathological behavior for MEST, predominantly a benign kidney tumor. In addition, documentation with more cases of MEST is needed to further understand its pathogenesis, clinical behavior, malignant potential, and optimal management.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
   References Top

1.
Michal M, Syrucek M. Benign mixed epithelial and stromal tumor of the kidney. Pathol Res Pract 1998;194:445-8.  Back to cited text no. 1
    
2.
Adsay NV, Eble JN, Srigley JR, Jones EC, Grignon DJ. Mixed epithelial and stromal tumor of the kidney. Am J Surg Pathol 2000;24:958-70.  Back to cited text no. 2
    
3.
Wein A, Kavoussi L, Campbell M, Walsh P. Campbell-Walsh Urology. 10th ed. Philadelphia: Elsevier Saunders; 2012. p. 1502.  Back to cited text no. 3
    
4.
Chu LC, Hruban RH, Horton KM, Fishman EK. Mixed epithelial and stromal tumor of the kidney: Radiologic-pathologic correlation. Radiographics 2010;30:1541-51.  Back to cited text no. 4
    
5.
Montironi R, Mazzucchelli R, Lopez-Beltran A, Martignoni G, Cheng L, Montorsi F, et al. Cystic nephroma and mixed epithelial and stromal tumour of the kidney: Opposite ends of the spectrum of the same entity? Eur Urol 2008;54:1237-46.  Back to cited text no. 5
    
6.
Svec A, Hes O, Michal M, Zachoval R. Malignant mixed epithelial and stromal tumor of the kidney. Virchows Arch 2001;439:700-2.  Back to cited text no. 6
    
7.
Nakagawa T, Kanai Y, Fujimoto H, Kitamura H, Furukawa H, Maeda S, et al. Malignant mixed epithelial and stromal tumours of the kidney: A report of the first two cases with a fatal clinical outcome. Histopathology 2004;44:302-4.  Back to cited text no. 7
    
8.
Jung SJ, Shen SS, Tran T, Jun SY, Truong L, Ayala AG, et al. Mixed epithelial and stromal tumor of kidney with malignant transformation: Report of two cases and review of literature. Hum Pathol 2008;39:463-8.  Back to cited text no. 8
    
9.
Mudaliar KM, Mehta V, Gupta GN, Picken MM. Expanding the morphologic spectrum of adult biphasic renal tumors – Mixed epithelial and stromal tumor of the kidney with focal papillary renal cell carcinoma: Case report and review of the literature. Int J Surg Pathol 2014;22:266-71.  Back to cited text no. 9
    
10.
Zou L, Zhang X, Xiang H. Malignant mixed epithelial and stromal tumor of the kidney: The second male case and review of literature. Int J Clin Exp Pathol 2014;7:2658-63.  Back to cited text no. 10
    
11.
Moslemi MK. Mixed epithelial and stromal tumor of the kidney or adult mesoblastic nephroma: An update. Urol J 2010;7:141-7.  Back to cited text no. 11
    
12.
Kamel MH, Davis R, Cox RM, Cole A, Eltahawy E. Enucleation/partial nephrectomy for large mixed epithelial stromal tumor and herniating into the pelvicalyceal system. Urol Ann 2014;6:377-80.  Back to cited text no. 12
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13.
Sun BL, Abern M, Garzon S, Setty S. Cystic nephroma/mixed epithelial stromal tumor: A benign neoplasm with potential for recurrence. Int J Surg Pathol 2015;23:238-42.  Back to cited text no. 13
    


    Figures

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


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