Magnetic resonance imaging features of pubic symphysis urinary fistula with pubic bone osteomyelitis in the treated prostate cancer patient.

Pubic bone osteomyelitis with pubic symphysis urinary fistula represents a debilitating complication of radiation and ablative treatments for prostate cancer. The definitive radiographic diagnosis of this clinical entity is not described. In this study, we characterize the plain film and magnetic resonance imaging findings of pubic osteomyelitis. We reviewed a database of prostate cancer survivors with diagnosed pubic osteomyelitis from 2011 to 2015. These patients underwent pelvic plain radiographs and magnetic resonance imaging with T1-weighted and fat-suppressed T2-weighted fast spin echo sequences. Intravenous gadolinium was utilized. The diagnosis was verified with extirpative surgery. 16 patients with diagnosed pubic osteomyelitis from 2011 to 2015 underwent imaging at our institution. All patients demonstrated increased signal on T2- weighted sequences and decreased signal on T1-weighted sequences along the pubic symphysis and the marrow of the involved pubic rami. Inflammatory myositis with diastasis of the pubic symphysis and cortical bone erosion were identified in the majority of patients. Fluid collections were identified in 75% of patients. 63% of conventional radiographs demonstrated no radiographic evidence of pubic osteomyelitis. Magnetic resonance imaging of pubic symphysis osteomyelitis in the prostate cancer survivor is characterized by high signal on T2-weighted images and low signal on T1-weighted images of the involved pubic rami, with the majority of patients demonstrating regional myositis. Imaging data combined with clinical assessment should prompt diagnosis and management of pubic osteomyelitis. Conventional radiography is generally insensitive to these findings. We consider magnetic resonance imaging to be the definitive diagnostic modality for this clinical entity.