TREM2 in Urological Malignancies and Benign Lesions: Mechanistic Convergence, Functional Heterogeneity, and Translational Perspectives: A Narrative Review.

Triggering receptor expressed on myeloid cells-2 (TREM2) is a key myeloid immune checkpoint for macrophage plasticity. However, its functional landscape in urology is still incomplete. This review addresses this gap by providing the first systematic synthesis of TREM2 in urological malignancies (bladder, prostate, and renal cell carcinomas) and benign conditions. We find a strong correlation between TREM2 upregulation and adverse clinical outcomes in these cancers. Importantly, we highlight the phenomenon of "mechanistic convergence": unlike the high context-dependency of other organ systems, TREM2 appears to drive progression in urological malignancies by a common convergent signaling hub, the PI3K/AKT pathway. This contrasts sharply with its metabolic role in benign prostatic hyperplasia and its protective role in non-malignant renal injury. We also consider the translational potential of TREM2 as a prognostic biomarker (specifically urine detection) and as a therapeutic target to reverse immunotherapy resistance.