Clinical History: 25-year old man with dysuria for 3 weeks

Diagnosis: Prostatic sarcoma

MR Technique:

Prostatic imaging was performed on a 3T MR system. (A) Sagittal T2-weighted TSE (TR/TE 7500/104ms), (B) coronal T2-weighted TSE (TR/TE 7354/104ms), and (C) axial T2-weighted TSE (TR/TE 7440/101) were acquired prior to the administration of intravenous contrast. Diffusion weighted imaging was performed along with calculation of an ADC map (D, E). Finally, dynamic contrast-enhanced T1-weighted VIBE (TR/TE 3.4-5.08/1.23-1.77ms) images were acquired in three orthogonal planes (F, G).

Imaging Findings:

Prostatic sarcomas are an uncommon, heterogeneous group of tumors arising from mesenchymal cells in and around the prostate. Non-enhanced MRI demonstrates an irregularly enlarged prostate gland displacing the rectum posteriorly and the bladder superiorly. T2WI exhibit an oval mass with solid components of intermediate to slightly increased signal intensity and irregular cystic areas. The lesion has well-defined margins with low signal intensity on T2WI. On DWI, the solid components of the lesion have heterogeneously increased signal intensity, corresponding to low ADC values. After injection of contrast, there is marked enhancement of the tumor as well as its capsule.