Primary Neoplasms of the Seminal Vesicles: A Narrative Review of Carcinoma and the Rarer Non-Epithelial and Biphasic Tumours.

Primary carcinoma of the seminal vesicle is an exceptionally rare genitourinary malignancy, with evidence limited largely to case reports and small retrospective series. Diagnosis requires exclusion of more common secondary involvement from prostate, bladder, or rectal carcinoma through integration of clinical findings, imaging, histomorphology, and immunohistochemistry. Patients typically present with nonspecific symptoms and often have locally advanced disease. Computed tomography identifies retrovesical masses, while magnetic resonance imaging provides superior local staging. Core biopsy may establish the diagnosis, although definitive classification may require resection. The typical immunophenotype is CK7-positive, often with CA-125 expression, and negative for PSA, PAP, and NKX3.1; however, no marker profile is invariable. A contemporary panel including GATA3, p63/p40, uroplakin markers, CK20, p53, CD44, CDX2, and SATB2 is important for excluding urothelial and intestinal primaries. Conventional papillary adenocarcinoma is the predominant histological type, with mucinous, clear cell, squamous, and neuroendocrine variants also reported. Non-carcinomatous primary seminal vesicle neoplasms, including germ-cell tumours, sarcomas, solitary fibrous tumour, and mixed epithelial and stromal tumour, form an important differential diagnosis. Complete surgical excision with negative margins is the treatment most consistently associated with prolonged survival in the reported cases and is generally regarded as the only potentially curative option, whereas radiotherapy, chemotherapy, and hormonal therapy are selectively used for advanced or recurrent disease. International registries and collaborative molecular studies are needed to improve diagnosis, treatment, and follow-up.