Testicular Plasmacytoma: A 25-Year Experience From a High-Volume Tertiary Center and Comparative Review of the Literature.

INTRODUCTION: Testicular plasmacytoma (TP) is a rare manifestation of plasma cell neoplasms (PCNs), with limited data regarding its presentation, management, and prognosis. We evaluated the clinicopathologic characteristics, treatment, and survival outcomes of TP in the largest single-institution cohort to date, supplemented by a contemporary literature review. MATERIALS AND METHODS: We retrospectively reviewed 26,523 patients with PCNs treated between 2000 and 2025. Patients with TP confirmed by imaging, biopsy, or orchiectomy were included. A focused literature review of TP published during the same period was performed. Demographic, clinicopathologic, treatment, and survival outcomes were analyzed. RESULTS: In our institutional cohort, 17 of 759 patients (2.2%) with extramedullary disease (EMD) had testicular involvement; no cases of solitary TP were identified. Median age at TP diagnosis was 58 years, and 82% had relapsed or refractory MM. IgG and IgA were the predominant immunoglobulin subtypes (50% each). Systemic anti-myeloma therapy following TP diagnosis was documented in 59% of patients. Concurrent bone marrow involvement was associated with significantly shorter overall survival (median overall survival, 6 vs. 55 months; log-rank P = .002). Median overall survival was 36 months. The literature review also identified 35 TP cases, including 6 solitary TP and 29 cases associated with multiple myeloma (MM). Solitary TP demonstrated favorable outcomes following orchiectomy. CONCLUSIONS: TP comprises two clinically distinct entities. Solitary TP has been associated with favorable short-term outcomes after orchiectomy alone. In contrast, TP associated with MM carries poor outcomes, particularly with concurrent bone marrow involvement, and requires early systemic therapy and multidisciplinary management.