Mixed Epithelial-Stromal Tumor (MEST) of Seminal Vesicle

Abstract

In contrast to the common tumors of the prostate, seminal vesicle demonstrates low potential for neoplastic proliferation. Of the rare primary seminal vesicle tumors, adenocarcinoma is the most common, but there are also rare seminal vesicle neoplasms which demonstrate epithelial and stromal components. These neoplasms have been described in the literature under various names, including "epithelial-stromal tumor," "cystic epithelial-stromal tumor," "cystadenoma," "cystomyoma," "mesenchymoma," "Müllerian adenosarcoma-like tumor," "phyllodes tumor," and "cystosarcoma phyllodes." The spectrum of reported mixed epithelial-stromal tumors (MEST) of seminal vesicle encompasses low, intermediate and high-grade tumors, but the precise distinction and nomenclature for these tumors remain unsettled. We propose a common nomenclature for these tumors, based on the review of published cases and 2 index cases from our practice, which represent the low-grade category. The first patient was 46 years old and presented with seminal vesicle neoplasm detected on routine rectal examination. The neoplasm measured 4 cm in greatest dimension, and completely replaced the left seminal vesicle. The tumor was circumscribed and consisted of multiple cysts separated by spindle-cell stroma. The second patient was a 60-year-old man, who had an incidental seminal vesicle neoplasm, which was discovered when he underwent a radical prostatectomy for a prostatic adenocarcinoma, (Gleason score 3+4, stage 3a). Both neoplasms contained hypercellular stroma, which was composed of uniform spindle cells, arranged in fascicles and interspersed between the glands. Both tumors lacked worrisome morphology, such as infiltrative borders, cell atypia, increased mitotic activity, hemorrhage, and necrosis. The stromal cells were reactive for estrogen and progesterone receptors, and desmin. The cysts and dilated glands were lined by epithelial cells, which were positive for cytokeratin 7 and were negative for prostate-specific antigen and prostate-specific acid phosphatase. The first patient underwent prostatectomy and was alive and without evidence of disease recurrence or progression after 11 years of follow-up. Similarly, the second patient had no evidence of disease recurrence or progression after 8 months of follow-up. We propose that term seminal vesicle "mixed epithelial-stromal tumor" be used to designate the tumors of the seminal vesicle containing epithelial and stromal components, with a distinction of grade based on the histologic features and the biological behavior. Histologic features to be evaluated for grade separation include stromal atypia, mitotic activity, nuclear pleomorphism, and tumor necrosis. Designations "low-grade MEST," "intermediate-grade MEST (uncertain malignant potential)," and "high-grade MEST" of seminal vesicle can be applied to these tumors to better characterize and study them in the future.

Robot‐assisted laparoscopic vesicule prostatectomy for mixed epithelial–stromal tumor of seminal vesicle

“…According to the most recent edition of the World Health Organization’s classification of Tumors, Pathology and Genetics, MEST including neoplasms previously called “cystadenoma,” “epithelial–stromal tumor,” “cystomyoma,” “cystic epithelial‐stromal tumor,” and “mesenchymoma.” These tumors were defined as “MEST which are biphasic tumors with stromal and benign epithelial components.” 3 Pathologically, MEST is classified as low, intermediate, or high grade. Reikie et al 1 . proposed a distinction of grade based on the histologic characteristics including stromal atypia, mitotic activity, nuclear pleomorphism, and tumor necrosis.…”

“…MEST is a biphasic tumor with stromal and benign epithelial components that was referred to by various terms until the most recent edition of the World Health Organization classification in 2016. However, SV MESTs have rarely been reported 1 . We herein report a patient with MEST originating from the right SV who underwent RALVP.…”

“…Primary SV tumors are rare. The most common malignant tumor of the SV is adenocarcinoma, followed by sarcoma and tumors with mixed epithelial and stromal components 1 . MEST is a biphasic tumor with stromal and benign epithelial components that was referred to by various terms until the most recent edition of the World Health Organization classification in 2016.…”

Laparoscopic vesiculectomy for large seminal vesicle cystadenoma

“…Benign primary tumours including cystadenomas are even rarer than malignant neoplasms. Seminal vesicle (SV) cystadenoma is a mixed epithelial‐stromal tumour (MEST) of Seminal Vesicle (Reikie, Yilmaz, Medlicott, & Trpkov, ). About 22 cases of cystadenoma of the SV have been reported in the English literature from the PubMed, Embase, Medline and the Web of Science databases since 1944 to March 2018 (Table ).…”

Rare primary seminal vesicle cystadenoma: computed tomography and magnetic resonance imaging findings

“…The histological finding in these cases demonstrated tumors composed of glands and cysts lined predominantly by cuboidal and columnar epithelium surrounded by fibrous stroma 27. Reikie et al 8. proposed that term seminal vesicle “mixed epithelial-stromal tumor” was used to designate the tumors of the seminal vesicle containing epithelial and stromal components, with a distinction of the grade based on the histologic features and the biological behavior.…”