Mixed Epithelial And Stromal Tumor Research Articles

Mixed Epithelial and Stromal Tumor of the Kidney with Polypoid Component Extending into Renal Pelvis and Ureter

Mixed epithelial and stromal tumor (MEST) of the kidney is an unusual benign neoplasm that predominantly occurs in middle-aged females. It typically appears as a well-circumscribed multiseptate mass with solid components on computed tomography (CT) or magnetic resonance image (MRI), reflecting its characteristics of an admixture of stromal proliferation and epithelial cells consisting of multiple cysts. We present a rare case of 61-year-old woman with MEST, which manifested as a multilocular cystic mass with a polypoid component protruding into the renal pelvis and ureter. To our best knowledge, this is the first case of MEST extending into the ureter.

Mixed Epithelial and Stromal Tumor of the Kidney: Radiologic-Pathologic Correlation

Mixed epithelial and stromal tumor (MEST) of the kidney is a rare, typically benign lesion that occurs predominantly in perimenopausal women. At computed tomography (CT), it typically manifests as a multiloculated cystic renal mass with a variable proportion of solid and cystic components and containing internal septa that demonstrate heterogeneous and delayed contrast material enhancement. MEST may mimic a variety of benign and malignant renal lesions, such as adult cystic nephroma, complex renal cyst, and cystic renal cell carcinoma. The preoperative diagnosis of MEST can be problematic, and most cases are treated surgically. However, CT with two-dimensional multiplanar reformation and three-dimensional volume rendering helps define the diagnostic features of MEST and can assist in surgical planning.

Mixed epithelial and stromal tumour (MEST) of the kidney: a clinicopathological report of three cases

Mixed epithelial and stromal tumour (MEST) of the kidney: a clinicopathological report of three cases

Adult Cystic Nephroma and Mixed Epithelial and Stromal Tumor of the Kidney: Clinical, Radiographic, and Pathologic Characteristics

Adult cystic nephroma (CN) and mixed epithelial and stromal tumor (MEST) are benign renal tumors readily distinguished from cystic renal cell carcinoma and other malignant variants based on histopathology. Clinical and radiographic data regarding these lesions are sparse, especially with respect to factors providing clinical suspicion for CN or MEST. Pathology of 22 CN (21 patients) and 10 MEST (9 patients) treated between 1987 and 2005 was re-reviewed according to 2004 WHO classification. Nineteen CN patients (90%) and 9 MEST patients (100%) were female and median ages were 55 (range: 39 to 79) and 52 (range: 39 to 67) years, respectively. Twenty-two patients (73%) presented symptomatically. CN were commonly Bosniak III lesions (77%), whereas 70% of MEST had solid enhancing components. An intrapelvic component was present in 5 CN (23%) and no MEST. Preoperative radiologic suspicion was documented in 36% of CN, but in only 1 patient with MEST. Nephron-sparing surgery was performed for 16 tumors (50%), including 5 suspected preoperatively and 3 that were 7 cm or greater. There was 1 case each of bilateral CN and MEST. Two patients with CN had concomitant renal cell carcinoma. One patient with MEST had sarcomatous component. At mean follow-up of 4.5 years (range: 1 to 18), no patient had novel or recurrent tumors develop. CN and MEST typically present symptomatically in perimenopausal women. Pedunculation of a multiloculated cystic lesion may allow for preoperative suspicion of these lesions in the proper clinical setting. Nephron-sparing surgery is the preferred treatment even for large and/or central lesions, if amenable.

Spontaneous Renal Mixed Epithelial and Stromal Tumor (MEST) in a Beagle

A mixed epithelial and stromal tumor (MEST) of the kidney was found in a 22-month-old female Marshall beagle. Histopathologically, this lesion was well demarcated and was composed of a mixture of epithelial and stromal elements. The epithelial elements, which contained columnar or ciliated columnar epithelia, had cystic and tubular growth patterns. The tubular lumina contained eosinophilic materials, which were positive for periodic acid Schiff and alcian blue (pH 2.5). Immunohistochemically, the epithelia were positively stained with proliferative cell nuclear antigen (PCNA) and showed co-expression of cytokeratin and vimentin. Morphologically, these proliferative ductal structures were suggestive of a primitive duct arising from the mesonephric or paramesonephric tubule. The stromal elements were characterized by proliferation of spindle cells embedded in a collagen-rich eosinophilic matrix. Additionally, stromal cells were positive for PCNA, vimentin and muscle markers (α-smooth muscle actin and desmin). Therefore, this lesion was ultimately diagnosed as a MEST of the kidney.

Cystic Nephroma and Mixed Epithelial and Stromal Tumor of Kidney: A Detailed Clinicopathologic Analysis of 34 Cases and Proposal for Renal Epithelial and Stromal Tumor (REST) as a Unifying Term

Cystic nephroma (CN) and mixed epithelial and stromal tumor (MEST) are rare benign renal neoplasms that have overlapping clinical and morphologic features, including predominance in middle-aged women, variably cystic architecture, eosinophilic cells, and hobnail cells lining the cysts and ovarian-type stroma. The aim of this study was to analyze and compare the histologic features and immunohistochemical profile of these tumors. We studied 34 cases from 5 large academic institutions. Twenty tumors were diagnosed as CNs, 18 in women and 2 in men, their age ranged from 24 to 63 (mean 48; median 50) years. Fourteen tumors were diagnosed as MESTs, all in women, their age ranged from 26 to 84 (mean 52; median 51) years. Histologically, all tumors were well-circumscribed except for one MEST. The stromal/epithelial ratio was approximately 2.3 in MESTs versus 0.3 in CNs; cellular ovarian-type stroma composed 45% of the stroma in MESTs and 12% of the stroma of CNs. Stromal hyalinization was prominent in both. Five MESTs showed stromal luteinization. In the epithelial component, the relative amount of large cysts, medium to small cysts, and phyllodes-type glands was: 65%/25%/10% in CNs versus 25%/40%/35% in MESTs. The epithelial component ranged from flat to cuboidal to hobnail cells in both types of tumors. No significant atypia of either component was seen, although the epithelial cells showed reactive changes. Immunohistochemical stains for estrogen receptors and progesterone receptors showed 62% and 85% positivity in the stromal component of MESTs versus 19% and 40% in CNs. CD10 positivity was seen in 77% of MESTs versus 50% of CNs, calretinin was seen in 69% of MESTs versus 41% of CNs, and inhibin in 42% of MESTs versus 36% of CNs, although the staining was focal. Follow-up in both categories of tumors (mean 3.2 y, median 3 y for CNs and mean 2.5 y, median of 2 y for MESTs) showed no evidence of recurrence or metastases in keeping with their benign nature. This study highlights the remarkable similarity between CN and MEST in sex predilection, age distribution, and morphologic attributes of both the epithelial and stromal components and immunohistochemical profile albeit with variation in individual categories with higher prevalence of stromal to epithelial ratio, prominent ovarian stroma, smaller cysts with phyllodes glands pattern and stromal luteinization being more common in MEST; and large cysts, thin septae and low stromal to epithelial ratio in CN. The presence of ovarian-type stroma and müllerian related immunohistochemical markers raises the possibility that these tumors may originate from müllerian remnants misplaced during embryogenesis. On the basis of detailed morphologic analysis of this series of CN and MEST, we propose a unifying term of "renal epithelial and stromal tumor" (REST) to encompass the spectrum of findings observed in these tumors at least until new molecular studies can prove or disprove this challenging hypothesis.

Mixed epithelial and stromal tumour (MEST) of the kidney: report of 14 cases with male and PEComatous variants and proposed histopathogenesis

This article adds new cases and variants of MEST with discussion of the histopathogenesis. Fourteen MEST were originally diagnosed as cystic nephroma which represents an incidence of 1.6% of renal neoplasms in adults. In females, the stromal component showed areas of müllerian differentiation with positive immunoreactivity for oestrogen (ER) and progesterone receptors (PR) and CD10. Immunoreactivity for HMB45 was identified in a single case having a leiomyomatous appearance. The epithelial component displayed features of müllerian epithelium and reactive renal tubular cells. In two male cases, MEST consisted of fibrous and smooth muscle stroma and cysts lined only by reactive renal tubular cells. Immunoreactivity for ER and PR was focal and weak. MEST represents a tumour developing from müllerian-like stromal cells in the kidney. The neoplastic stroma encroaches on the renal tubules and has the potential to stimulate the growth of the renal tubules by contact, with development into cysts. Furthermore, the müllerian stroma likely induces the renal tubules to differentiate into müllerian-like epithelium. Melanocytic differentiation of the stroma may occur which represents the PEComatous variant. MESTs in males were histopathologically slightly different from those in females due to the different hormonal milieu.

Cystic nephroma (multilocular cyst) and mixed epithelial and stromal tumor of the kidney: a spectrum of the same entity?

The recently described mixed epithelial and stromal tumor (MEST) of the kidney and adult cystic nephroma (CN) (multilocular cyst) are rare benign cystic renal neoplasms that are composed of epithelial and stromal elements. Consensus criteria for distinguishing these entities have not been well established. Our objective in this study was to evaluate cases of CN and MEST to define the morphological, immunophenotypic, and clinical features of these two entities. Eleven cases from the files of a single institution diagnosed from 1996 to the present as either CN or MEST were reviewed. Architecturally, all lesions were composed of multiple noncommunicating cysts lined by a single layer of epithelial cells. All cases had areas with increased stromal cellularity and 8 cases had ovarian-like stroma present at least focally within the tumor. No stromal or epithelial cell atypia, blastemal elements, or increased mitotic activity was appreciated. The immunoprofile was also similar in the 7 cases stained and included epithelial reactivity with keratin and CAM 5.2 and stromal reactivity with estrogen receptor, progesterone receptor, smooth muscle actin, WT-1, vimentin, and focal desmin. All cases have acted in a benign fashion with no history of recurrence or metastasis. We propose that CN and MEST of the kidney represent a spectrum of the same entity. If the diagnosis of CN is limited to cases that are comprised entirely of thin fibrous-walled cysts, all 11 of our cases would be classified as MEST.

Benign mixed epithelial stromal tumor of the renal pelvis with exophytic growth: case report

BackgroundMixed epithelial and stromal tumor (MEST) is a distinctive benign composite neoplasm of the kidney predominantly seen in females mostly in the perimenopausal period. Although these tumors are known to arise from renal pelvis, our case was distinct in that it had no intrapelvic component growing in exophytic fashion.Case reportA 35 year old female patient presented to us with vague abdominal pain. She had undergone excision of bilateral ovarian cystic masses for cystic teratoma twelve years earlier. A computed tomography scan of abdomen and pelvis showed a 9 × 7 cm uniformly solid mass with poor contrast enhancement situated in the inferomedial aspect of the left kidney. On exploration, the mass was arising from the inferior and anterior aspect of left renal pelvis, and was attached to it with a narrow pedicle. There was no adherence or attachment to the renal parenchyma. The mass was excised preserving the kidney. Microscopically, the tumor was composed of large collagenized areas containing bundles of spindle cells and several 'microcysts' lined by cuboidal epithelium suggestive of a benign mixed epithelial stromal tumor.DiscussionMixed epithelial tumors usually present in perimenopausal women as a partially cystic mass. Tumors are composed of irregular mixtures of cystic and solid areas, glands with variable complexity and distribution and the stromal component is characterized by a spindle cell proliferation. Commonly, it arises from the renal parenchyma and pelvis and nephrectomy is advocated to manage these tumors.ConclusionMEST is a distinctive benign tumor of the kidney that should be distinguished from other renal neoplasms. MEST arising from the renal pelvis and growing exophytically is a rare entity. The overall prognosis is favorable.