Low grade epithelial stromal tumour of the seminal vesicle

Abstract

Background: The mixed epithelial stromal tumour is morphologically characterised by a mixture of solid and cystic areas consisting of a biphasic proliferation of glands admixed with solid areas of spindle cells with variable cellularity and growth patterns. In previous reports the seminal vesicle cystoadenoma was either considered a synonym of or misdiagnosed as mixed epithelial stromal tumour. The recent World Health Organisation Classification of Tumours considered the two lesions as two distinct neoplasms. This work is aimed to present the low-grade epithelial stromal tumour case and the review of the literature to the extent of establishing the true frequency of the neoplasm.

Case presentation: We describe a low-grade epithelial stromal tumour of the seminal vesicle in a 50-year-old man. Computed tomography showed a 9 x 4.5 cm pelvic mass in the side of the seminal vesicle displacing the prostate and the urinary bladder. Magnetic resonance was able to define tissue planes between the lesion and the adjacent structures and provided useful information for an accurate conservative laparotomic surgical approach. The histology revealed biphasic proliferation of benign glands admixed with stromal cellularity, with focal atypia. After 26 months after the excision the patient is still alive with no evidence of disease.

Conclusion: Cystoadenoma and mixed epithelial stromal tumour of seminal vesicle are two distinct pathological entities with different histological features and clinical outcome. Due to the unavailability of accurate prognostic parameters, the prediction of the potential biological evolution of mixed epithelial stromal tumour is still difficult. In our case magnetic resonance imaging was able to avoid an exploratory laparotomy and to establish an accurate conservative surgical treatment of the tumour.

Figure 1

Axial spin-echo T1-weighted (a) and axial (b) and sagittal T2-weighted (c) MRI showed a large, well-defined, multilocular pelvic mass in the side of the seminal vesicles, contiguous to the posterior wall of the urinary bladder and the prostate. On T1 and T2-weighted images the mass showed internal septations that delimited heterogeneous iso- hyperintense areas with proteinaceus content.

Figure 2

The cut surface showed multilocular cists of varying size and shapes. The segments of both the right and the left vas deferens were evident. Inset: the external surface was yellow, smooth and glistening.

Figure 3

Microscopically the tumour showed cistically dilatated glands containing pale eosinophilic intraluminal secretions and lined by one to two layers of cuboidal or low columnar cells (H&E ×40).

Figure 4

The stromal cells were spindle-shaped and showed pleomorphism. The stroma was at least focally densely cellular and tended to condense around distorted glands (H&E ×200).

Figure 5

The stromal cells show positivity for AML (a)(×400), Vimentin (b)(×600) and CD 34 (c)(×600).