Mesenchymal Tumors of the Prostate.

Prostatic mesenchymal tumors encompass various benign and malignant neoplasms that may derived from the intrinsic prostatic stroma or from associated elements including muscle, connective tissue, blood vessels, and neural structures. The differential diagnosis of these tumors is broad and encompasses prostatic epithelial processes that demonstrate prominent spindle cell morphology, as well as mesenchymal tumors that secondarily involve the prostate. Careful morphologic examination, clinical history, and judicious use of a limited panel of immunohistochemical markers and molecular tests aid in the proper diagnosis of these lesions. This article provides a structured guide for the analysis and diagnosis of both benign and malignant prostatic mesenchymal lesions and highlights key features that distinguish these entities within the differential diagnosis of prostatic spindle cell lesions.