When the pelvic water balloon isn't the bladder. A rare case of a seminal vesicle cystic tumour causing lower urinary tract symptoms

Mixed epithelial-stromal tumours (MEST) of the seminal vesicle (SV) are a rare type of cystic tumour containing both epithelial and stromal components and have few reported cases in literature. These tumours have varying presenting symptoms ranging from asymptomatic to those with urinary retention, haematuria or abdominal pain.1 This case's purpose is to describe the diagnosis and management of a cystic SV mass presenting with non-specific lower urinary tract symptoms (LUTS). A 62-year-old male was referred to clinic with severe nocturia and storage LUTS refractory to medical therapy. Initial renal tract ultrasound and computed tomography (CT) urogram reported significant prostatomegaly (396 cc) and a 64 mL post-void residual. However, digital rectal examination revealed a small, benign prostate with a separate fluctuant mass present and prostate specific antigen (PSA) was 0.3 ng/mL. Pelvic magnetic resonance imaging (MRI) (Fig. 1) was performed, given the discordant radiology report and clinical examination findings, and demonstrated a large, rectovesical thin-walled, multi-septated cystic mass arising from the SV. A small, irregular nodular component was present in the left anteroinferior aspect. Subsequent Fluorodeoxyglucose (FDG)-positron emission tomography (PET) showed mild FDG accumulation (standardized uptake value max 3.4) in the nodular component of the cyst, but no FDG avid lymphadenopathy or distant lesion. Following multi-disciplinary review, transperineal aspiration of the cyst yielded 450 mL serous fluid with negative cytology and culture. The patient reported significant improvement of his LUTS in the first week post aspiration, however the symptoms rapidly recurred with cyst re-accumulation on imaging. He then underwent a successful laparoscopic SV excision (Fig. 2) with resolution of his symptoms. Operative histology demonstrated a low grade mixed epithelial and stromal tumour of the seminal vesicle. Given the rarity of SV cystic lesions, they can easily be misdiagnosed with initial imaging and biopsy. Similarly, their rarity has ensued in the lack of a standardized treatment and surveillance regimes post resection. This case highlights the need for thorough patient pre-operative work-up and review of imaging to ensure an optimal outcome from the surgical management for the treatment of LUTS. Kevin Y. Zhuo: Conceptualization; data curation; writing – original draft; writing – review and editing. Basil Razi: Writing – review and editing. James Kovacic: Conceptualization; writing – review and editing. Andrew Shepherd: Conceptualization; supervision; writing – review and editing. Ankur Dhar: Conceptualization; data curation; supervision; writing – review and editing. Krishan Rasiah: Conceptualization; supervision; writing – review and editing. Open access publishing facilitated by The University of Sydney, as part of the Wiley - The University of Sydney agreement via the Council of Australian University Librarians. Informed written patient consent was attained to publish this case. All research was conducted in accordance with the Declaration of Helsinki.